I
HAVE great pleasure in returning my most sincere thanks to various
naturalists, both for intrusting to me their collections of Fossil
Cirripedia, and for allowing me, whenever it was advisable, to clear
the specimens from their matrix. Although an entire stranger to many of
the gentlemen to whom I applied, I have in every instance received the
most courteous acquiescence to my demands. To Mr. Fitch, of Norwich, I
here beg to return my thanks, for having allowed me to keep, during
several months, his unrivalled collection of Cirripedia from the Upper
Chalk of Norwich,—the fruit of twenty years' labour. Mr. Bowerbank has
given me the freest use of his fine collection, rich in specimens from
the Gault. Mr. Wetherell placed in my hands his beautiful and unique
specimen of Loricula pulchella, and other species. Professor
Buckman sent me, of his own accord, a fine series of the valves of Pollicipes
ooliticus,
the most ancient Cirripede as yet known, discovered and named by him.
To Messrs. Flower, Searles Wood, F. Edwards, Harris, S. Woodward,
Tennant, and other gentlemen, I owe the examination of several species
new to me. Mr. Morris and Professor E. Forbes have, in their usual kind
manner, supplied me with much valuable information, and with the loan
of many specimens. To Mr. James de C. Sowerby I must express my thanks
for the valuable aid rendered to me by the loan of the original
specimens figured in the 'Mineral Conchology;' and for the pains
exhibited in the drawings here published.

Professor
Forchhammer, of Copenhagen, not only placed at my disposal many
valuable specimens deposited in the Geological Museum of the
University, but applied to Professor Steenstrup, who, in the most
generous manner, sent me the collection in the Zoological department,
including the highly valuable original specimens of his excellent
Memoir on the Fossil Cirripedia of Denmark and Scania. Subsequently,
Professor Steenstrup sent me a second large collection, the fruit of
the indefatigable labours of M. Angelin, in

Scania:
all these northern specimens have been of the greatest use to me in
illustrating the British species. Having applied to Professor W. Dunker
of Cassel, for some of the species described by various German authors,
he not only sent me many specimens out of his own collection, but
procured from Messrs. Roemer, Koch, and Philippi, other specimens of
great value; and to these most distinguished naturalists I beg to
return my very sincere thanks. Lastly, I may be permitted to state,
that I hope very soon to have another and more appropriate opportunity
of publicly expressing my gratitude to various gentlemen, who for many
months together have left in my hands their large and valuable
collections of recent Cirripedia, and who have assisted me in every
possible way. I will here only state, that it was owing to the
suggestion and encouragement of Mr. J. E. Gray, of the British Museum,
that I was first induced to take up the systematic description of the
Cirripedia, having originally intended only to study their anatomy. To
all the foregoing gentlemen, I shall ever feel under the deepest
obligations.

INTRODUCTION.

————————

THE
CIRRIPEDIA, both recent and fossil, have been much neglected by
systematic naturalists: the fossil species have, however, been more
attended to than the recent. Professor Steenstrup has published1
an excellent monograph on the Danish and Scanian Cretaceous species:
Mr. J. de Carle Sowerby has given good plates of several British valves
in the Mineral Conchology; and F. Roemer2 has illustrated,
by rather indifferent figures, though clear descriptions, various
German forms. Other less important notices have appeared by several
authors. As yet, however, no monograph has been produced on the whole
group. The present volume is confined to the Lepadidæ or
Pedunculated Cirripedia; and it so happens that the introduction,
under
the form of notes, of a few foreign species (which are necessary to
illustrate the British species), serves to render this Monograph
tolerably complete; that is, as far as the specimens collected on the
Continent (judging from published accounts) serve for this end,—for we
shall immediately see that certain valves are requisite in each genus.

It
is unfortunate how rarely all the valves of the same species have been
found coembedded; it is evident that, with the exception of some few
species, the membrane which held the valves together, decayed very
easily, as it does in recent Pedunculated Cirripedes. Hence, in the
great majority of cases, the several valves have been found separate.
Hitherto it has been the practice of naturalists to attach specific
names indifferently to all the valves; and as in each species there
are
from three to five or six different kinds of valve, there would have
been, had not the whole group been much neglected, so many names
attached to each species. On the other hand, it has occurred in several
instances, that many valves belonging to quite different species have
been grouped together under the same name. To avoid these great evils,
I have fixed on the most characteristic valves, one in each of the two
main genera, and taking them as

typical,
have never, except in one instance where several valves were known all
to belong to the same individual, and in another instance in which a
valve was very remarkable, attached a specific name to any other one. I
have, however, in two cases retained names already given to certain
other valves, as they presented remarkable characters, and were almost
certainly distinct. In Scalpellum I have taken the Carina or Keel-valve
(i. e. dorsal valve of most authors) as typical; and in
Pollicipes, the
Scuta (i. e. the inferior lateral valves of most authors): it
would have
been desirable to have taken the same valve in both genera; but it so
happened that the Carina has been much more frequently collected than
any other valve in Scalpellum, in which genus it is highly
characteristic; whereas in Pollicipes, it is apt to present less
striking characters than the Scuta, which are, moreover, commoner in
most collections. In almost all the Lepadidæ the Terga (i. e.
the upper
or posterior lateral valves) are not characteristic, and are
particularly liable to variation. Although only certain valves in each
genus thus receive specific names, yet from the conditions of
embedment, several of the other valves can often be safely attributed
to the same species.

Much confusion in
nomenclature will, I think, be avoided by the plan here adopted; but
the study of Fossil Cirripedia must, I fear, owing to the variability
of the valves, as seen in some fossil species, and as inferred from
what so commonly occurs with recent species, ever remain difficult. In
very many of those recent species, of which large series have passed
through my hands, several of the valves have varied so much, that had I
seen only certain specimens from the opposite poles of the series, I
should unhesitatingly have ranked them as quite distinct species: on
the other hand there are some recent forms—for instance, some species
of Lepas, and again Pollicipes cornucopia, and elegans
of Lesson—which are perfectly distinct, but which it would be hopeless
to attempt discriminating when fossilized, without quite perfect
specimens. It should be borne in mind, that the recognition of the
Fossil
Pedunculated Cirripedes by the whole of their valves and peduncle, is
identical with recognising a Crustacean by its carapace, without the
organs of sense, the mouth, the legs, or abdomen: to name a Cirripede
by a single valve is equivalent to doing this in a Crustacean by a
single definite portion of the carapace, without the great advantage of
its having received the impress of the viscera of the included animal's
body: knowing this, and yet often having the power to identify with
ease and certainty a Cirripede by one of its valves, or even by a
fragment of a valve, adds one more to the many known proofs of the
exhaustless fertility of Nature in the production of diversified yet
constant forms.

I must allude to one more unfortunate cause
of doubt in the classification of the extinct Lepadidæ, namely, the
difficulty in attributing the separated valves to the two main genera
of Scalpellum and Pollicipes; for the chief distinction between these
two close genera in the recent state, lies in the number of the valves,
and this can very rarely be ascertained in fossil specimens. At first I
determined to follow those authors who have united both genera under
Pollicipes; but reflecting that I had twelve recent and

above thirty-seven fossil species, with almost the certainty—as we
shall presently see—of very many more being discovered, this plan
seemed to me too inconvenient to be followed. There are six recent
species which I intend, in a future work, to include under Scalpellum.
Four of them have been raised by Dr. Leach and Mr. Gray to the rank of
genera; two other unnamed species have certainly equal, if not
stronger, claims to the same rank; so again the six recent species of
Pollicipes have similar claims to be divided into three genera, thus
making nine genera for the twelve recent species of Scalpellum and
Pollicipes. In the majority of cases it would be eminently difficult to
allocate the fossil species in these nine genera; nevertheless, taking
the characters necessarily used for the generic divisions of all the
other recent Pedunculated Cirripedes, there can be no doubt that the
formation of the above nine genera might be justified, that is, if we
are allowed to neglect mere classificatory utility as an element in the
decision, and further, if we are invariably bound to make as far as
possible all genera of exactly the same value. As far as utility in
classification is concerned, it appears to me clear that the
institution of
so many genera, until many more species are discovered, is highly
disadvantageous: with respect to making all genera of exactly
equal value, this, though eminently desirable, appears to me almost
hopeless; I know not how to weigh the value of slight differences in
different valves; or whether a difference in the maxillæ or mandibles
be the more important: anyhow, in this particular case, if we raised
the six recent species of Scalpellum into six genera, they assuredly
would not be distinct to an exactly equal degree. Under these
circumstances I have followed a middle term, and kept Scalpellum and
Pollicipes distinct,—genera easy to be recognised in a recent
state,—which renders the classification of the fossil species, though
always difficult and liable to many errors, somewhat easier than if
both genera were united into one, and much easier than if the above
nine genera were admitted.

APTYCHUS.

Before passing to more general considerations, I must
offer a few remarks on the genus Aptychus, or Trigonellites,
inasmuch as quite lately a distinguished naturalist, M. D'Orbigny,1
has adopted, and with much ingenuity supported, the view that these
anomalous bodies are Pedunculated Cirripedia. It cannot be denied that
the general form and lines of growth closely resemble those of the
Scuta or lateral inferior valves in Lepas or Anatifa: nor can it be
denied, from what we know of recent species, that the Terga (upper
lateral valves) and Carina (dorsal valve), which on M. D'Orbigny's view
must be considered as absent, are the most likely valves to disappear
from abortion. But there are points of difference which, as it appears
to me, are of far greater importance than the

resemblance in mere outline. The peculiar cancellated structure,
which is almost visible on the external surface even to the naked eye,
is wholly unlike anything known amongst Cirripedia; a thin polished
slice of the valves of Lepas and of Aptychus, viewed under a high
power, are as unlike as anything can well be.1 In Aptychus
the lines of growth are conspicuous on the inner or concave surface,
and indistinguishable or not plain on the outer surface; whereas in
Lepas exactly the reverse holds good. Again, in some specimens it
appears, that additions are made to the shell on the exterior edge of
the growing margin, instead of on the inner edge, as in Cirripedia. In Aptychus
latus,
there is a rather deep internal fold along the whole of that margin,
through which the cirri are supposed to have been protruded, and this
is unlike anything which I have met with in Cirripedes. In all the
species of Aptychus, the two valves are much the most frequently,
though not invariably, found widely opened, and attached together,
either exactly or nearly so, by the two margins through which the cirri
must have been protruded. Now in all true fossil pedunculated
Cirripedes, the valves are found either separate, which is the
commonest case, or when held together, those on the opposite sides
almost exactly cover each other, for there is nothing in the structure
of Cirripedia tending to open the valves like the ligament in bivalve
shells. How comes it, then, that the specimens of Aptychus, even those
found within the protected chambers of Ammonites, thus generally have
their valves widely gaping? Even if we pass over this difficulty, is it
not strange that the valves should always have been held together by
that margin, which in the recent condition is supposed to have been
open for a considerable portion of its length, for the exsertion of the
cirri; whereas, in not one single instance, as far as I have seen, are
the two valves held together by the opposite margin, which in the
recent state, on the idea of Aptychus having been a Cirripede, must
have been continuously united by membrane.

There
is another argument against Aptychus having been a Cirripede, which
will have weight, perhaps, with only a few persons: in Pollicipes, the
main growth of all the valves is downwards; in Lepas or Anatifa, as
well as in most of the allied genera, the main growth of the Scuta and
of the Carina (i. e. lower lateral, and dorsal, or valves,) is
in a
directly reversed direction, or upwards. Now Pollicipes is the oldest
known genus of Cirripedes, having been found in the Lower Oolite,
whereas hitherto Lepas is not certainly known to have been discovered
even in the newest Tertiary formation. So again within the limits of
the genus Scalpellum, I know of only two cretaceous species in which
the Scuta grow upwards and downwards, and only one case in which the
Carina has this double direction of growth; whereas in the recent and
one Miocene species, these valves usually grow both upwards and
downwards. Hence it would appear that there is some relation between
the age of fossil Lepadidæ and the upward or downward direction of

1
When I had the slices made, I did not know of H. von Meyer's paper on
Aptychus, in the 'Acta Acad. Cæs. Leop. Car.,' vol. xv, Oct. 1829,
tab.
lviii and lix, fig. 13, in which perfectly accurate sections are given
of the microscopical structure of Aptychus lævis.

the lines of growth in their valves. Aptychus, according to M.
D'Orbigny, existed during the Carboniferous system, at a period vastly
anterior to the oldest known Pollicipes, yet on the idea of its having
been a Cirripede, the growth of its valves (Scuta) must have been
upwards, as in the most recent forms; and it was allied to Lepas, that
genus which, in the order of creation, and in the manner of growth,
stands at the opposite end of the series from Pollicipes. From the
several reasons now given, it does not appear to me that Aptychus,
until weightier evidence is adduced, can be safely admitted as a
Cirripede.

Geological History.— No true Sessile Cirripede1
has hitherto been found in any Secondary formation; considering that
at
the present time many species are attached to oceanic floating objects,
that many others live in deep water in congregated masses, that their
shells are not subject to decay, and that they are not likely to be
overlooked when fossilized, this seems one of the cases in which
negative evidence is of considerable value. Mr. Samuel Stuchbury,
moreover, (to whom I am deeply indebted for much information, and the
loan of his beautiful collection of recent species,) has assured me
that vast numbers of fossil secondary corals have passed through his
hands, and that he has carefully looked without success for those
genera which commonly inhabit living corals. Sessile Cirripedes are
first found in Eocene deposits, and subsequently, often in abundance,
in the later Tertiary formations. These Cirripedes now abound so under
every zone, all over the world, that the present period will hereafter
apparently have as good a claim to be called the age of Cirripedes, as
the Palæozoic period has to be called the age of Trilobites. There is
one apparent exception to the rule that Sessile Cirripedes
are not found in Secondary formations, for I am enabled to announce
that Mr. J. de C. Sowerby has in his collection a Verruca (= Clysia,
Clytia, Creusia, Ochthosia) from our English chalk: but this genus,
though hitherto included amongst the Sessile Cirripedes, must, when its
whole organisation is taken into consideration, be ranked in a distinct
family of equal value with the Balanidæ and Lepadidæ, but perhaps more
nearly related to the latter than to the Sessile Cirripedes. Hence the
presence of Verruca in the Chalk is no real exception to the rule that
Sessile Cirripedes do not occur in Secondary formations; on the
contrary, it harmonises with the law, that there is some relation
between serial affinities of animals, and their first appearance on
this earth.

The oldest known pedunculated Cirripede is a
Pollicipes, discovered by Professor Buckman in the Stonesfield Slate in
the Lower Oolite: two species of the same genus have been described by
Mr. Morris from the Oxford Clay, in the middle Oolite. I have

1 Dr. Petzholdt has described and figured
(Jahrbuch, 1842, p. 403, tab. x), a Balanus carbonaria
from the carboniferous system; but as neither the operculum, the
structure of the shell, the number of the valves, nor their manner of
growth, can be made out or are described, the evidence appears quite
insufficient to admit the existence of this genus at so immensely a
remote epoch. Bronn, in the 'Index Palæontologicus,' gives, under
Tubicinella, a cretaceous species; I have unfortunately not been able
to consult the original work cited.

not heard of any Cirripede having been as yet discovered in the
Upper Oolite, or in the Wealden formation. During the deposition of the
great Cretaceous System, the Lepadidæ arrived at their culminant point; there were then three genera, and at least thirty-two species, some
occurring in every stage of this system. Besides the thirty-two
certainly known cretaceous forms, and several other doubtful ones, I
believe that very many more will yet be discovered; I infer this from
the fact, that in almost every collection lent to me for examination,
although very small, I have found some new species. I have three or
four species from the Gault; from five to eight in the Lower Chalk,
and
from nine to twelve species in the Upper Chalk (not including the
Faxoe, Scanian, and Maëstricht stage); and of these nine to twelve
species, five have been found by one collector, Mr. Fitch, in one
locality, namely near Norwich. In Scania M. Angelin has found no less
than nine or ten species, all belonging to the upper or Maëstricht
stage of the Chalk. These fossils, judging from the habits of recent
species of the same genera, were probably attached to fixed, or nearly
fixed, objects at the bottom of the sea. Now at the present day, of
attached Pedunculata (reckoning even Crustacea and Echinidæ as fixed
objects), the whole Mediterranean and New Zealand can boast each only
of three species, in both cases including Alepas, which is destitute of
calcified valves and therefore not likely to be fossilized; Australia
has three species; Madeira has four species, including one with very
small and imperfectly calcified valves; the great Phillipine
Archipelago, however, has afforded, owing to the labours of Mr. Cuming,
as many as five species, though including one with horny valves, and a
Lithotrya which lives embedded on the beach. Therefore since we already
have nine or ten fossil species from one locality, and from the same
stage of the chalk, we may admit that the pedunculated Cirripedes
arrived during the upper part of the Cretaceous system at their
culminant point.

Although, for this family,
the number of species were considerable during the Cretaceous period,
the individuals were mostly rare. I infer this from the small number of
specimens in all collections; for instance, Mr. Fitch, who has
assiduously collected for twenty years in the chalk near Norwich,
possesses in his entire collection only nine keel-valves of Scalpellum
maximum, and six of S. fossula; he has two Scuta (and
with regard to these valves, it must be remembered, that each
individual had two) of Pollicipes striatus, two of P.
fallax, and four of P. Angelini.
This occasional want of a relation, within the same region, between the
number of the species in any given genus, and of the individuals
appertaining to such species, is a singular fact, and has been strongly
insisted on by Dr. Hooker, in regard to the Coniferous trees of the
southern hemisphere: one would naturally have expected, that where
circumstances favoured the existence of numerous species of a genus,
they would likewise have favoured the multiplication of the individuals
in all or most of such species; but this, as we here see, has not
always been the case.

In the Eocene, Miocene, and Pliocene
Tertiary deposits, I know only of two species of Scalpellum, and two of
Pollicipes, with indications of two or three other species, all
distinct

from recent forms. It is a rather singular fact, considering the
present wide distribution of the genus Lepas or Anatifa, and the
frequency of the individuals, that not a single valve known certainly1
to belong to this genus, or to any of the closely-allied genera, has
hitherto been found fossil.

The
oldest known cirripede is, as we have seen, a Pollicipes from the lower
Oolite, and it does not differ conspicuously from some of the recent
species of the same genus; so, again, the cretaceous Scalpellum
fossula, and the eocene S. quadratum are certainly very
nearly related to the recent S. rutilum (nov. spec.). Loricula
alone is a genus perfectly distinct from all living Cirripedia; and I
may here add that of the Tertiary Sessile Cirripedes, I have hitherto
not seen a single new generic form. This persistence of the same genera
is somewhat remarkable, considering that amongst ordinary Crustacea
nearly all the Secondary species belong to extinct genera;2
it should, however, be borne in mind that Limulus has survived from the
Palæozoic period to the present day. The Oolitic, Cretaceous, Tertiary,
and recent species of Lepadidæ are all different from each other. By
looking at the annexed Table, and putting out of question the species
of which the age is uncertain, we have five common to two stages of the
chalk; that is assuming for the present that the classification of the
stages of the chalk commonly used and here followed, is correct. Pollicipes
glaber is common to three, and, I believe, to four stages. Scalpellum
arcuatum
occurs in the Chalk-marl, and upper Greensand, and therefore this
species also extends through three stages; but there is a slight
difference between the specimens from the upper and lower stages, which
some authors might perhaps consider specific. If fossil cirripedia had,
like most recent species, very wide horizontal or geographical ranges,
then, in accordance with a law now generally admitted, a considerable
vertical range in some of the species is not improbable.

I
may here observe that I am assured by Professors Forchammer and
Steenstrup, that the formations of Scania and Westphalia are equivalent
to that of Faxoe; and hence to that of Maëstricht. I have called these
formations the " Maestricht formation," to distinguish them
from the common upper or white Chalk.

1 In a mere catalogue, published without
descriptions, in the 'Jahrbuch' for 1831, p. 155, by Hoenninghaus, Anatifa
cancellata
is given as a tertiary species: Mr. G. B. Sowerby has stated, in his '
Genera of Shells,' that he has seen a Tertiary specimen of this genus,
but he cannot remember which valve it was.

N.B.—In the Carina of Scalpellum, A is
the tectum; B the parietes; C the intra-parietes.

Figure II.

Scutum of POLLICIPES.

Figure III.

Tergum of POLLICIPES.

Whoever
will refer to the published descriptions of recent and fossil
Cirripedia, will find the utmost confusion in the names given to the
several valves; thus, the valve named in the above woodcut, the
Scutum,
has been designated by various well-known naturalists as the "
ventral,"
the " anterior," the " inferior," the " ante-lateral," and the
" latero-inferior" valve; the first two of these titles have,
moreover,
been applied to the rostrum or rostral valve of Sessile Cirripedes. The
Tergum has been called the " dorsal," the " posterior," the "
superior,"
the " central," the " terminal," the " postero-lateral," and the
" latero-superior" valve. The Carina has received the first two of
these
identical epithets, viz. the " dorsal" and the " posterior;" and
likewise
has been called the " keel-valve." The confusion, however, becomes far
worse, when any individual valve is described, for the very same margin
which is anterior or inferior in the eyes of one author, is the
posterior or superior in those of another; it has often happened to me
that I have been quite unable even to conjecture to which margin or
part of a valve an author was referring. Moreover, the length of these
double titles is inconvenient.

Hence, as I intend to describe all the recent and fossil species, I
have thought myself

justified
in giving short names to each of the more important valves, these being
common to the Pedunculated and Sessile Cirripedes.

The
title of peduncle, which is either naked or squamiferous, requires no
explanation; the scales and lower valves are arranged in whorls, which
I have called by the botanical term of Verticillus. The part supported
by the peduncle, and which is generally, though not always, in recent
species protected by valves, I have designated the Capitulum.

I have applied the term Scutum
to the most important and persistent of the valves, and which can
almost always be recognised by the hollow giving attachment to the
adductor scutorum muscle, from the resemblance which the two valves
taken together bear to a shield, and from their office of protecting
the front side of the body. From the protection afforded by the two Terga
to the dorso-lateral surface of the animal, these valves have been
thus called. The term Carina
is a mere translation of the name already used by some authors, of
Keel-Valve: in the genus Scalpellum, in which this valve is taken as
typical, I have found it quite necessary, with fossil specimens, to
distinguish the roof (see Woodcut, I,) or exterior surface, as the
tectum (A); the inflected sides, as the parietes (B); and in several
species in the upper half of the valve, the intra-parietes (C): the
expressions of apex, basal margin, and inner margin, as applied to the
Carina, require no explanation. The rostrum has been so called from its
relative position to the Carina or keel. There is often a sub-carina
and a sub-rostrum.

The remaining valves have been called Latera;
there is always one large upper one inserted between the lower halves
of the Scuta and Terga, and this I have named the Upper Latus or
Latera; the other Latera in Pollicipes are numerous, and require no
special names; in Scalpellum, where there are at most only three pair
beneath the Upper Latera, it is convenient to speak of them (vide
Woodcut, I,) as the Carinal, Infra-median, and Rostral
Latera.

As
each valve, especially amongst the fossil species, requires a distinct
description, I have found it indispensable to give names to each
margin. These have mostly been taken from the name of the adjoining
valve, (See Woodcut, I.) In Pollicipes the margin of the Scutum
adjoining the Tergum and Upper Latus, is not divided (Woodcut, II,)
into two distinct lines, as in Scalpellum, and is therefore called the
tergo-lateral margin; a narrow portion or slip along this side of the
valve may be seen (Woodcut, II,) to be formed of upturned lines of
growth; this is often of service in classification, and I have called
it the tergo-lateral slip or segmentum tergo-laterale. In Scalpellum
(Woodcut, I,) these two margins are separately named Tergal and
Lateral. The angle formed by the meeting of the basal and lateral or
tergo-lateral margins, I call the baso-lateral angle; that formed by
the basal and occludent margins, I call, from its closeness to the
Rostrum, the rostral angle. In Pollicipes the Carinal margin of the
Tergum (Woodcut, III,) can be divided into an upper and lower carinal
margin.

That margin in the Scuta and Terga which opens and shuts
for the exsertion and retraction of the cirri, I have called the
Occludent margin.

During
the periodical growth of the valves, especially when they are thick and
massive, it happens in several species that the underlying corium
deserts their upper ends or umbones, which consequently become marked
by lines or ridges of growth, as I have called them, though perhaps
lines of recession would have been more strictly correct. Such valves,
consequently, have their upper ends projecting from and beyond the
capitulum, and are said to project freely or liberè;
this is often more especially the case with the Carina in Pollicipes,
and in a lesser degree with the Terga.

From
the peculiar curved position which the animal's body occupies within
the capitulum, I have found it far more convenient (not to mention the
confusion of nomenclature already existing) to apply the term Rostral
instead of ventral, and Carinal instead of dorsal, to almost all the
external and internal parts of the animal. Cirripedes have generally
been figured with their surfaces of attachment downwards, hence I have
termed the lower margins and angles the Basal, and those pointing in an
opposite direction the Upper; strictly speaking, the exact centre of
the usually broad and flat surface of attachment is the anterior end of
the animal, and the upper tips of the Terga, the posterior end of that
part of the animal which is externally visible; but in some cases, for
instance in Coronula, where the base is deeply concave, and
where the width of the shell far exceeds the depth, it seemed almost
ridiculous to call this, the anterior extremity; as likewise does it
in
Balanus to call the united tips of the Terga, lying deeply within the
shell, the most posterior point of the animal as seen externally.

Cirripedia having a peduncle, flexible, and provided with muscles.
Scuta1 furnished only with an adductor muscle: other
valves,
when present, not united into an immovable ring.

Besides
the brief characters here given others might have been added, drawn
from the softer parts of the animals, but as this Volume treats only of
Fossil species, they would have been in this place superfluous. Nor
have I thought it advisable to give here any definition of the
Sub-class Cirripedia, or of the Order which contains both the Lepadidæ
and Balanidæ, that is the Pedunculated and Sessile Cirripedes; for the
characters would likewise have had to be derived almost entirely from
the softer parts of the animal. It may, however, be worth stating, that
by following the metamorphoses of the Cirripedia, it can be clearly
shown that the capitulum together with the peduncle, in the
Pedunculated
Cirripedes, and that the shell together with the operculum in the
Sessile Cirripedes, that is the whole of what is externally visible,
consists simply of the first three segments of the head. In many
Crustacea the carapace, formed by the backward production of the three
anterior rings of the head, covers the dorsal surface of the thorax,
and in some it encloses the limbs and mouth. This is likewise the case
with the Cirripedia, and it is only the wonderful elongation of the
anterior part of the head, its fixed condition, and the absence of
external eyes and antennæ, which gives to the Cirripedia their peculiar
character, and has hitherto prevented the homologies of these parts
from having been recognised.2

1 The meaning of this and all other terms
is given in the Introduction at page 9.

2 Nevertheless,
in some Stomapoda, more especially in Leucifer of Vaughan Thompson,
the anterior part of the head is only a little less elongated, compared
with the rest of the body, than in the Cirripedia. That accomplished
naturalist, M. J. D. Dana (Silliman's 'American Journal,' March,
1846,)
has stated that " the pedicel of Anatifa corresponds to a pair of
antennæ in the young:" although the peduncle or pedicel is undoubtedly
thus terminated, this view cannot, I think, be admitted. In the larva,
the part anterior to the mouth is as large, in proportion to the rest
of the body, as in some mature Cirripedia: this anterior part supports
only the eyes, antennæ, and two small cavities furnished with large
nerves, which I

I
may further state, that in the several Orders of Cirripedia such
important differences of structure are presented, that there is
scarcely more than one great character by which all Cirripedia may be
distinguished from other Crustacea: this character is, that they are
attached to some foreign object by a tissue or secretion (for at
present I hardly know which to call it), which debouches, in the first
instance, through the prehensile antennæ of the larva, the antennæ
being thus embedded and preserved in the centre of the basis. The
cementing substance is brought to its point of debouchement by a duct,
leading from a gland, which (and this is perhaps the most remarkable
point in the natural history of the Class) is part of and continuous
with the branching ovaria. When we look at a Cirripede, we, in fact,
see only a Crustacean, with the first three segments of its head much
developed and enclosing the rest of the body, and with the anterior end
of this metamorphosed head fixed by a most peculiar substance,
homologically connected with the generative system, to a rock or other
surface of attachment.

suspect to
be auditory organs; this part, therefore, I think, must unquestionably
consist of the first two or three segments of the head: within it,
even
before the larva moults, the incipient striæless muscles and ovaria of
the peduncle can be distinctly traced: immediately after the moult, we
see this anterior part converted into a perfect peduncle; and for some
time afterwards certain coloured marks, indicating the former position
of the (so called) olfactory cavities and of the cast-off compound
eyes, are still preserved. The prehensile antennæ are not cast off, for
they are fastened down by the cementing substance, and are thus
preserved in a functionless condition, with their muscles absorbed;
after a time even the corium is withdrawn from within them. From the
above and other coloured marks, and from the antennæ being preserved,
it is easy to point out, in the peduncle of a young though perfect
Lepas, the exact point which each part occupied in the head of the
natatory larva.

Since the above was
written, I find that Lovén has taken the same view of the homologies of
the external parts of the Cirripedia: in his description of his Alepas
squalicola,
(Ofversigt of Kongl. Vetens., &c., Stockholm, 1844, pp. 192-4,) he
uses the following words: " Capitis reliquæ partes, ut in Lepadibus
semper, in pedunculum mutatæ et involucrum," &c.; his
involucrum is the same as the Capitulum of this work.

Valves
12 to 15 in number. Latera of the lower whorl, four or six, with their
lines of growth generally directed towards each other. Sub-rostrum1
very rarely present. Peduncle squamiferous, most rarely naked.

CHARACTERS OF THE VALVES IN FOSSIL SPECIES.

Carina
narrow, bowed inwards, widening but little from the apex to the basal
margin, having parietes much inflected, and generally separated by
distinct ridges from the tectum, and having in many species
intra-parietes, which are sometimes produced upwards beyond the umbo,
so as to make it sub-central; lines of growth on the parietes very
oblique. Scuta generally only slightly convex and thin, four-sided, the
tergal
and lateral margins distinctly separated by an angle.

The
first of the above two paragraphs contains the true Generic description
(here leaving out the softer parts), as applicable to recent and, as
far as known, to fossil species: the second paragraph has been drawn
up
to aid any one in classifying the characteristic valves, when found
separated, as is most frequently the case with all fossil Pedunculata.
The first or proper Generic characters would have been more precise,
had it not been for the existence of one recent species, the S.
villosum (Pollicipes villosus, Leach, Calentica Homii,
J. E. Gray,) which leads into the next genus Pollicipes. I mention this
species in order to confess, that had the valves been found separately,
and their number unknown, they would certainly have been included by me
under Pollicipes, although, taking the whole organisation into
consideration, I have determined to include this species under
Scalpellum. I need not

1 The meaning of this and
all other
special terms is given in the Introduction at p. 9.

here
repeat the remarks made in the Introduction on the great difficulties
in classifying the recent species, and still more the fossil species of
Scalpellum. I may, however, here state that should the S. vulgare
be hereafter kept distinct in a genus to itself, S. magnum
would have to go with it. Should a recent species, which in a future
work I shall describe under the name of S. rutilum, be
generically separated, it will probably have to bear the name of
Xiphidium, from its alliance to the Eocene X. quadratum of
Sowerby, to which species the cretaceous S. fossula and
several other forms are apparently closely allied. These latter
species, however, are likewise closely allied to the Scalpellum
ornatum, which Mr. Gray has already raised to the rank of a genus
under the name of Thaliella. There are some fossil species,
as S. arcuatum, and simplex and solidulum,
which I cannot rank particularly near any recent forms. Mr. Sowerby
founded the genus Xiphidium on the umbo in the Carina being situated at
the apex, and on its growth being consequently exclusively downwards.
This is likewise the case with the recent S. rutilum; but I
shall have occasion to show, under S. magnum,
that the upward growth of the Carina in that and other species of the
genus, depends merely on the intra-parietes, which are present in many
species, meeting each other and being thus produced upwards. Moreover,
in the recent S. ornatum, the position of the umbo is
variable, according to the age of the specimen; in half-grown
individuals being seated at the apex, and in large specimens being
sub-central, as in S. vulgare, magnum, and other
species. I should have been very glad to have retained the genus
Xiphidium, but taking into consideration the whole organisation of the
six recent species, I can only repeat that we must either make six
genera of them, or leave them altogether, and this latter has appeared
to me the most advisable course.

Sexual Peculiarities.—For
reasons stated in the Introduction, I have kept the genera Scalpellum
and Pollicipes distinct; but I may mention, in order to call attention
to a point of structure which may hereafter be discovered in some
fossil species, that I was much influenced in this decision by some
truly extraordinary sexual peculiarities in all six recent species of
Scalpellum. Scalpellum ornatum is bisexual; the individual
forming the ordinary shell, is female; each female has two males (a
case of Diandria monogynia),
which are lodged in small transverse depressions, one on each side,
hollowed out, on the inner sides of the Scuta, close above the slight
depressions for the adductor scutorum muscle; in S. rutilum
(nov. spec.) two males are lodged in the same place on each side, but
rather in concavities in the valve, than in distinct depressions. As
these are the two recent species most nearly related to several
Cretaceous and Eocene forms, we might expect to find similar
depressions in some fossil species; but as yet I have not succeeded in
distinctly finding such. The male cirripedes are very singular bodies;
they are minute, of the same size as the full-grown larva; they are
sack-formed, with four bead-like rudimental valves at their upper ends; they have a conspicuous internal eye; they are absolutely destitute of
a mouth, or stomach, or anus: the cirri are rudimental and furnished

Inside view of the scutum in Scalpellum ornatum.
(A) is the depression for the adductor muscle.

with
straight spines, serving, apparently, to protect the entrance of the
sack: the whole animal is attached, like ordinary cirripedes, first by
the prehensile antennæ, and afterwards by the cementing substance; the
whole animal may be said to consist of one great sperm-receptacle,
charged with spermatazoa; as soon as these are discharged, the animal
dies.

A far more singular fact remains to be told: Scalpellum vulgare
is like ordinary cirripedes, hermaphrodite, but the male organs are
somewhat less developed than is usual; and, as if in compensation,
several short-lived males are almost invariably attached on the
occludent margin of both Scuta, at a spot marked by a fold (not thus
caused), as may be seen on the inside view of this valve in the fossil S.
magnum,
which, in all probability, was furnished with them. I have called these
beings complemental males, to signify that they are complemental to an
hermaphrodite, and that they do not pair like ordinary males with
simple females. In Scalpellum vulgare, the complemental male
presents only slight specific differences from the male of S.
ornatum.
It would be foreign to the purpose of this volume here to enter on
further details; nor should I have touched on the subject, had I not
wished specially to call attention to the presence of cavities on the
under sides of the Scuta above the pits for the adductor muscle. I will
only add, that in the other species of Scalpellum, the complemental
males are more highly organised, and are furnished with a mouth and
prehensile cirri; the valves are more or less rudimental in the
different species; these complemental males are not always present,
and
are never attached to young hermaphrodites; when present, they adhere
in such a position, that they can discharge their spermatozoa into the
sack of the hermaphrodite: their attachment does not affect the form
of
the valves.1

Description of Valves.—It
will, I think, be most convenient to confine the following description
to the fossil species of the genus. No one specimen has been found
quite perfect; but, judging from analogy, the capitulum was probably
formed of fourteen valves in S. magnum, and of twelve in the
remaining species. These valves are commonly smooth,

1 Exactly analogous facts are presented,
though more conspicuously, by the two species of the genus Ibla.
Before examining this genus, I had noticed the complemental males on Scalpellum
vulgare, but had not imagined even that they were Cirripedia. Ibla
Cumingii
(as I propose to call a new species collected by Mr. Cuming, at the
Philippines) is bisexual; one or two males being parasitic near the
bottom of the sack of the female. These males are small, are supported
on a long peduncle, but are not enclosed in a capitulum (such
protection being here unnecessary), are furnished with a mouth,
ordinary trophi, stomach, and anus: there are only two pair of cirri,
and these are distorted, useless and rudimentary; the whole thorax is
extremely small; there is no penis, but a mere orifice beneath the
anus
for the emission of semen; hence Ibla Cumingii is exactly
analogous to Scalpellum ornatum. On the other hand, the
closely allied
Australian Ibla Cuvierii, like Scalpellum vulgare,
is hermaphrodite, but has, in every specimen opened by me, a
complemental male attached to near the bottom of the sack; this
complemental male differs only about as much from the male of Ibla
Cumingii, as the female J. Cumingii differs from the
hermaphrodite form of I. Cuvierii.
I intend hereafter to give detailed anatomical descriptions and
drawings of the males and complemental males of Ibla and Scalpellum.

but
in two or three species are marked with longitudinal ridges; they are
generally rather thin; this, however, is a character which is variable
even in the same species.

Carina narrow,
widening but little from the apex downwards, slightly or considerably
curved inwards, with the umbo seated at the uppermost point: S.
magnum,
however, must be excepted, for in it the umbo is sub-central, and the
valve almost angularly bent, as will be described in detail under that
species. The apex rarely projects freely; but this is a variable point
in the same species; the basal margin is either pointed, rounded, or
rarely truncated. The chief character by which this valve can be
recognised, as belonging to the genus Scalpellum, is the distinct
separation by an angle, (see woodcut, Fig. 1, in the Introduction,)
often surmounted by a prominent ridge, of the tectum or roof, from the
parietes, which are either steeply or rectangularly inflected; the
lines of growth on these parietes are oblique. A still more conspicuous
character is afforded by the part (when present), which I have called
the intra-parietes; these give to the valve a pieced appearance, and
seem
let in, to fill up a vacuity between the upper part of the
carina and the terga, and this is their real office; they are
separated
from the true parietes by a ridge, which evidently marks the normal
outline of the valve. These intra-parietes are flat, and they have a
striated appearance rather different from the rest of the valve; and
the lines of growth on them are extremely oblique, almost parallel to
the inner margins of the valve.

Scuta very
slightly convex; four-sided; the tergal and lateral margins being
divided by a slightly projecting point or angle; and this is the chief
character by which the scuta of this genus can be distinguished from
those of Pollicipes. The umbo is seated at the uppermost point, except
in S. magnum, and in S. (?) cretæ (Tab.
I, fig. 1 c,
and fig. 11 c),
in which species the lines of growth, instead of terminating at the
angle separating the lateral and tergal margins, are produced upwards,
so that the valve is added to above the original umbo. In S.
tuberculatum (fig. 10 d), the scuta present an
intermediate character between that in ordinary fossil species, for
instance in S. fossula (fig. 4 a), and in S.
magnum and cretæ.
The occludent margin is nearly straight, or slightly curved; both it
and the lateral margin form nearly rectangles with the basal margin,
which is nearly straight. Internally the depression for the adductor
scutorum is generally, but not always, very plain; sometimes the valve
is filled up and rendered solid in the upper part above the adductor
muscle. The apex sometimes projects freely, and is internally marked
with lines of growth. The internal occludent margin, or edge, is also
often marked by lines of growth, and the part thus marked, close above
the adductor muscle, sometimes becomes suddenly wider; this is caused
by some slight change in the position of the animal's body during
growth.

Terga flat, either trigonal or rhomboidal,
and, in the former case, sometimes so much elongated, with the carinal
margin so much hollowed out, as to become almost crescent-shaped; a
slight furrow often runs from the upper to the basal angle. Internally,
in the upper part, there is in some species a little group of small
longitudinal ridges, unlike anything I have seen in recent species, and
serving, I apprehend, to give firmer attachment to the corium.

Rostrum unknown in any fossil species; but judging from
recent species, it probably existed in all.

Upper latera known only in three species; in S. magnum
it is irregularly oval, with the umbo central: in S. quadratum
and fossula, five-sided, with the umbo at the upper angle:
in
the eocene S. quadratum, however, an inner ledge very
slightly projects beyond the two upper sides, and first indicates a
tendency to upward growth. Rostral latera, known only in S.
magnum and quadratum, they are transversely elongated,
narrow, and small. Infra-median latera unknown; they
probably
existed only in S. magnum. Carinal latera, known in
S. magnum, quadratum, fossula, solidulum, and maximum;
in the first species they are transversely elongated; in the three
latter, of an irregular curved shape, and flat. In the fossil and
recent species, the rostral and carinal latera grow chiefly in a
direction towards each other; so that their umbones are close to, or
even seated exteriorly to, the carinal and rostral ends of the
capitulum. Peduncle, calcified scales are known only in one
species, the S. quadratum; but they probably existed in all
:
the naked peduncle, however, of the recent S. Peronii must
make us cautious on this head.

From the close affinity between this species and the recent Scalpellum
vulgare,
we may confidently infer that the capitulum consisted of fourteen
valves, which are all preserved in Mr. Wood's collection, with the
exception of the infra-median latera and of the rostrum. This latter
valve would, no doubt, be rudimentary, and it has been overlooked by
naturalists even in the recent species. The chief difference, excepting
size, between these two species, is in the form of the rostral and
carinal latera, but unfortunately these valves are extremely variable.
It might even be maintained, with some degree of probability, that S.
magnum was only a variety of S. vulgare. The valves of S.
magnum are all thicker, stronger, more rugged, and considerably
larger than in S. vulgare. Taking

1
I have followed Mr. Morris in his Catalogue, in adopting this name from
the MS. of Mr. Searles Wood, to whose kindness I am greatly indebted
for having placed in my hands the whole of his large series of valves
of this species.

the
largest scutum, tergum, carina and upper latera in Mr. Wood's
collection, they are very nearly double the size of the same valves in
the largest specimen of S. vulgare seen by me, namely from
near Naples, which had a capitulum eight tenths of an inch in length;
and they are more than double the size of the same valves in any
British specimen. Scalpellum magnum probably had a capitulum
one inch and a half in length.

Carina (Tab. I, fig. 1 b and f)
abruptly, almost rectangularly bent, with the umbo of growth seated
just above the bend, at about one third or one fourth of the entire
length of the valve from the upper point; form linear, with the lower
part slightly wider than the upper. Exteriorly the surface is rounded
with no central ridge, excepting near the umbo, where the narrowness of
the whole valve gives it a carinated appearance; basal margin rounded.
From the umbo two faint ridges run to each corner of the basal margin,
separating the steeply-inclined parietes from the roof,—a character of
some importance in the cretaceous species of this genus: outside of
these two ridges there are other two ridges, not extending down to the
basal margin, and separating the parietes from the intra-parietes,
which latter being united at their upper ends, and produced upwards,
form that part of the carina which is above the umbo. By comparing the
lateral views of the carina of the cretaceous S. fossula
(fig. 4 c),
and of this species, it will be seen, that the apparently great
difference of the umbo of growth being either at the apex, or, as in
this species, sub-central, simply results from the lines of growth of
the intra-parietes meeting each other, the valve being thus added to at
its upper end. The carina of S. magnum, examined internally,
is found often to be narrower under the umbo than either above or below
it, a character I have not seen in the recent S. vulgare. The
lateral width or depth of the valve (measured from the umbo to the
inner edge) is also greater than in S. vulgare:
this portion is internally filled up and solidified. No part of the
apex of the valve projected freely. The longest perfect specimen which
I have seen, is half an inch in length; but I have noticed fragments
indicating even a greater size.

Scuta (fig. 1 c)
much elongated, trapezoidal, slightly convex; umbo placed on the
occludent margin at about one fourth of the entire length of the valve
from the apex, so that the valve grows upwards and downwards. Occludent
margin straight, slightly hollowed out above the umbo, forming rather
less than a right angle with the basal margin, which latter is at right
angles to the lateral margin. The tergal margin is separated from the
lateral by a slight projection (beneath which the margin is a little
hollowed out), and from this projection there runs a ridge, often very
conspicuous, to the umbo. The part above the ridge, stands at rather a
lower level than that below it, and the lines of growth on it are
generally less distinct. This is connected with the fact, as
ascertained in S. vulgare, that the valve, during its
earliest stage, grows only downwards, the ridge thus indicating the
original form of the valve and tendency of the lines of growth. On
comparing that part of the scuta beneath the umbo and ridge, in the
present species (Tab. I, fig. 1 c), with the whole valve in
some other species, for instance in S. fossula (fig. 4 a),
in which the umbo is seated at the apex, as it was in the first
commencement of growth in S. vulgare and magnum, it

will be seen how closely the two valves resemble each other. The
scutum of S. tuberculatum (fig. 10 d) is
intermediate in its manner of growth between those of S. magnum
and fossula.
Internally, the impression for the adductor muscle is deep: on the
occludent margin, close to the umbo, there is a deep fold, which is
connected with the growth of the upper part of the valve being
subsequent to that of the lower part. There is very little difference
between this valve and that of S. vulgare; the upper part,
however, appears to be always thicker. Length of largest specimen one
eighth of an inch.

Terga (fig. 1 d)
triangular, sometimes approaching to crescent-shaped; flat and thin,
though the thickness of the valve varies. Carinal margin straight, or
very slightly hollowed out; in its upper part there is a barely
perceptible prominence marking the limit of the upward extension of the
carina. Basal angle blunt, rounded; from it a line, formed by the
convergence of the zones of growth, runs near and parallel to the
carinal margin, up to the apex. Occludent margin about equal in length
to the scutal; parallel to the former, a slip of the valve is rounded
and slightly protuberant, and this portion projects a little on the
scutal margin. A very small portion, or none, of the apex of the valve
projected freely. This valve is somewhat narrower, and the scutal
margin
straighter, than in S. vulgare.

Rostrum unknown, no doubt rudimentary, probably
quadrangular.

Upper latera (fig. 1 e)
flat, oval, with the upper half a little pointed; the lower margin
shows traces in a varying degree consisting of three sides. The
surface, but chiefly of the lower half, is faintly marked with striæ
radiating from the centre. The umbo lies in the middle, and from it two
slight ridges, first bending down, diverge on each side. In Scalpellum
vulgare this valve (which is very similar in shape to that of S.
magnum)
at the first commencement of its growth, as with the scuta, is added to
only downwards; and thus the two diverging ridges mark the form which
the valve originally tended to assume: bearing in mind that the basal
margin tends to be three sided, if we remove that part of the valve
above the ridges which have been superadded to the original form, we
shall have a five-sided valve, essentially like that in the S.
quadratum and S. fossula (fig. 3 e, and fig. 4
d).

Rostral latera (fig. 1, g to k)
elongated, widening gradually from the umbo to the opposite end, which
is equably rounded: umbonal half free, curling outwards; the internal
surface of the other half (h) is nearly flat and regularly
oval, with its end towards the umbo pointed; the freely projecting
portion varies from nearly one half to one third of the entire length
of the valve; but in one distorted specimen it was only one
sixth of this length. The width, also, of the valve varies (g
and h), compared to its length. This valve, compared with its
homologue in S. vulgare,
differs more than any of the preceding valves; it is proportionally
larger, and the internal or growing surface is oval, instead of being
oblong and almost quadrangular; and the umbonal or freely projecting
portion in S. vulgare is only one sixth or one seventh of the
entire length of the valve.

Infra-median latera unknown.

Carinal latera (fig. 1, l to n)
narrow, thick, much elongated, widening gradually from the umbo to the
opposite end, which is rounded and obliquely truncated. Surface,
exteriorly

flat;
internally convex. The umbonal, freely projecting portion is sometimes
more than half, sometimes only about one third, of the entire length of
the valve. This portion curls outwards and likewise upwards. The degree
of curvature and the width (m and n), in proportion
to the length, varies. The upper and lower margins are approximately
parallel to each other; the umbonal end of the growing surface is
bluntly pointed. This valve differs from its homologue in S.
vulgare,
in being larger, much narrower in proportion to its length, more
massive, and with a far larger portion of the umbonal end freely
projecting; also in the approximate parallelism of the upper and lower
margins, and in the umbonal end of the growing surface being pointed
instead of square. In S. vulgare the upper margin is much
more curled upwards than the lower, and the freely projecting portion
is only one fifth of the entire length of the valve.

Taking
the largest specimens in Mr. Wood's collection, the freely projecting
portions of the carinal latera must have stuck out like horns, curling
from each other and a little upwards, for a length of a quarter of an
inch. So again, the much flattened horns of the rostral latera, curving
from each other, but not upwards, must have projected half an inch
beyond the probably rudimentary rostrum. The capitulum must have
presented a singular appearance, represented in the imaginary restored
figure (fig. 1 a), with its pair of projecting horns at both
ends.

Peduncle; calcareous scales unknown, but undoubtedly they
existed.

Varieties:
the variation in the rostral and carinal latera has already been
pointed out. In Mr. Wood's collection there are numerous scuta, terga,
carinæ, and carinal latera, from Sutton; and these are all smaller
than
those above described, which come from Sudbourne, and than some others
in Sir C. Lyell's collection from Gedgrave. All these places, however,
belong (as I am informed by Mr. Wood) to the same stage of the
Coralline Crag. In the Sutton specimens the carinal latera show the
same character as in those from Sudbourne, but the carina apparently is
not internally so much narrowed in under the umbo; this, however, is a
character which is conspicuous only in the larger Sudbourne specimens,
and anyhow cannot be considered as sufficient to be specific.

I
may take this opportunity of stating, that in Mr. Harris's collection
of organic remains from the chalk detritus, at Charing, in Kent, I have
found the upper part of a carina of a very young and minute Scalpellum,
which cannot be distinguished from this species; but considering the
state of the specimen, it would be extremely rash to believe in their
identity. All the known cretaceous species have the umbo at the apex,
so that the Charing specimen differs remarkably from its cretaceous
congeners.

My
materials consist of a slab of rock, belonging to Mr. S. Wood, almost
made up of the valves of this species, of two beautiful specimens in
Mr. F. Edwards's collection, and of some excellent drawings from Mr.
Dixon's specimens by Mr. James de C. Sowerby, in the Mineral Conchology.1
The valves in several of these specimens are nearly in their proper
positions, though there is not one in which they have not slipped a
little. Their relative positions are given, I believe nearly correctly,
in Pl. I, fig. 3 a. Their number I have little doubt was
twelve. This, however, includes a rostrum, probably almost rudimentary,
the existence of which I infer only from the analogy of all recent
species. Mr. J. Sowerby supposed that there were, as in S. vulgare,
four pair of latera (and therefore fourteen valves in all), but I
conclude, without hesitation, that there were only three pair, as in
the recent S. rutilum (nov. spec.), to which the S.
quadratum is much more nearly allied than to S. vulgare.

Capitulum: elongated, probably composed of twelve valves. Carina
(fig. 3, d, i, k),
rather narrow, slightly and regularly bowed and widening from the apex
to the basal margin, which latter is bluntly pointed, or almost
rounded; internally deeply concave; externally with the tectum and
parietes flat, and at right angles to each other;—hence the carina is
square-edged, and its specific name has been given to it. Scuta
(fig. 3, b, h)
oblong, occludent margin slightly arched, forming with the basal rather
less than a right angle; tergal margin separated by a just perceptibly
projecting point from the lateral margin, which latter is very slightly
hollowed out; whole valve slightly convex, with a trace of a ridge
running from the apex to the baso-lateral angle. Internally (h),
there is a large pit for the adductor scutorum, above which there is a
slight depression or fold marked with c urved lines of growth, and in
this depression on each side complemental males

1
Some small fragments were found by Mr. Wetherell, and are noticed in
his Paper in the fifth volume of the 'Geolog. Transactions,' entitled
" Observations on a Well dug on the south side of Hampstead Heath."

were probably attached. Terga (fig. 3 c)
triangular, large, flat, basal angle bluntly pointed; apex slightly
projecting, as a solid horn; occludent margin very slightly arched. Rostrum
unknown; judging from the narrowness of the umbones of the rostral
latera, it was probably minute or rudimentary. Upper latera
(fig. 3 e)
large compared with the lower valves, flat, five-sided, with the two
upper sides the longest; of the three lower sides, that corresponding
with the end of the rostral latera is generally (especially in young
specimens) the shortest. Umbo seated at the uppermost angle; but in
full-sized specimens, a narrow ledge has been added, during the
thickening and growth of the valve, along the two upper margins, and
consequently round the apex. Rostral latera (fig. 3 f)
extremely narrow, three or four times as long as wide; considerably
arched, extending parallel to the basal margin of the scuta; widening
gradually from the umbo to the opposite end, which is obliquely
truncated in a line (as I believe) corresponding with the shortest side
of the upper latera; inner surface smoothly arched; during growth,
the
narrow rostral half of the valve becomes much thickened, and at the
same time added to along its upper margin, thus producing a solid,
sloping, projecting edge; umbo slightly projecting. Carinal latera
(fig. 3 g)
almost flat, not elongated, of a shape difficult to be described;
approaching to a triangle, with curved sides, and one angle
protuberant.

Peduncle.
The calified scales are apparently large in proportion to the valves
of the capitulum; transversely elongated, pointed at both ends, and
more or less crescent shaped.

Affinities. This
species was generically separated from Scalpellum by Mr. Dixon, as I am
informed by Mr. James Sowerby, solely owing to the umbo of growth in
the carina being at the apex, instead of being sub-central, as in
S. vulgare;
but I need not here repeat the reasons already assigned for at present
keeping all the recent and fossil species under the same genus. In the
umbo of growth, in the carina and scuta being seated at their upper
ends, in the square form of the carina, in there being only three pair
of latera, and in the large size of the upper latera, this eocene
species is much more closely allied to S. rutilum (nov.
spec., of which the habitat is unfortunately not known,) than to
any other recent species. In some respects, however, I may remark, S.
rutilum is even more closely related to certain cretaceous forms.
To S. ornatum, the nearest recent congener of S. rutilum,
the present species is allied by the narrowness of the rostral latera,
and by the large size and peculiar shape of the scales on the peduncle
:
the carinal latera perhaps rather more resemble those of S. vulgare
than of any other recent species. Certainly, all the
affinities
in S. quadratum point to S. rutilum, ornatum, and vulgare,
and these three recent species are characterised by having males or
complemental males attached to the sides of the orifice of the sack,
whereas, in the other species, they are elsewhere attached; hence it
is
that I believe that males were probably lodged in the slight
depressions described on the inner sides of the scuta; but the
depression is not here nearly so distinctly developed as it is in the
recent S. ornatum, and more resembles the fold on the
occludent edge of the valve in S. vulgare: I must add that
folds of this nature do not necessarily imply the presence of males.

Carina, having
intra-parietes, with the tectum bordered on each side by large,
protuberant, flat-topped ridges; basal margin bluntly pointed; upper
latera five sided, with two slight ridges extending from the apex to
the basal margin.

General Remarks.
My materials consist of two specimens, belonging to Mr. Fitch, most
kindly lent me for examination; in which, taken together, the scuta,
terga, carina, upper and carinal latera, are seen almost in their
proper places. In Mr. J. Sowerby's collection there is a single scutum,
also, from Norwich. From analogy with the eocene S. quadratum
and the recent S. rutilum, I have little doubt that there
were only three pair of latera; and that, probably, there was a
rostrum. With respect to the exact position of the carinal
latera, there is, as also in the case of the S. quadratum,
some little doubt.

Capitulum
narrow, elongated, probably composed of 12 valves, which are moderately
strong, and apparently closely locked together. The length of the
capitulum in the largest specimen was 1.1 of an inch.

Carina (fig. 4, c, g, h)
strong, moderately bowed, extending far up between the terga, almost to
their upper ends; rather narrow throughout, gradually widening from
the
apex to the base; lines of growth plain; no portion projects freely.
The tectum or central portion is slightly arched, subcarinated, and
bounded on each side by flat-topped, protuberant ridges: the tectum
terminates downwards in a blunt point (the two margins forming an angle
of rather above 90°), which projects beyond the bounding ridges; the
tectum and the two bounding ridges all widen gradually from the apex
towards the base. The parietes are channelled or concave; they do not
extend so far down as the ridges bounding the tectum. In the upper half
of the carina, we here first see the additional parietes, or
intra-parietes, which appear as if formed subsequently to the other
parts, and let in between the ordinary parietes of the carina, and the
terga. It has been already shown, under S. magnum, that it is
the intra-parietes produced upwards, which causes in that and some
other species the umbo of the valve to be sub-central.

Scuta (fig. 4, a, f)
oblong, the basal margin only slightly exceeding half the entire length
of the valve; valve strong, rather plainly marked with lines of growth; basal margin at nearly right angles to the occludent margin; tergal
margin separated by a slightly-projecting

point
from the lateral margin, which in the lower half is slightly
protuberant; tergal margin straight, with the edge thickened and
slightly reflexed. A distinct, square-edged ridge (therefore formed by
two angles) runs from the umbo to the baso-lateral angle, which is
itself obliquely truncated. Internally (f), there is a large
and deep pit for the adductor scutorum. Terga (fig. 4 b)
triangular, flat, large, fully one third longer than the scuta; basal
half much produced; basal angle pointed; from it to the apex or umbo
there runs a narrow, almost straight furrow, at which the lines of
growth converge—it runs at about one third of the entire width of the
tergum (in its broadest part) from the carinal margin. Parallel to the
occludent margin, and at a little distance from it, there runs a wide,
very shallow depression up to the apex. The scutal margin is not quite
straight, about a third part, above a slight bend corresponding with
the apex of the upper latera, being slightly hollowed: from the above
bend a very faint ridge runs to the apex of the valve. Upper latera
(fig. 4 d)
large, flat, with five sides, of which the two upper are much the
longest; the basal side is next in length, and the scutal side much
the
shortest. As far as I can judge of the positions of the lower valves,
with respect to the upper latus, I believe, that the rostral latera,
probably, abutted against the shortest of the three lower sides; that
the carina ran along the one next in length, and the carinal latera
along the middle basal side, which I suppose extended in an oblique
line, and not parallel to the base of the capitulum: the two upper
long
sides no doubt touched the scuta and terga. The umbo of growth is at
the apex; there is, however, a trace of a projecting ledge added round
the upper margins during the thickening of this upper part of the
valve. Two slight ridges run from the apex to the two corners of the
middle of the three lower sides. Carinal latera (fig. 4 e)
:
these are not quite perfectly seen: the umbo forms a sharp point,
whence the valve rapidly expands and curves apparently downwards and
towards the upper latera. Near one margin there is a very narrow
furrow, and on the other a wide depression, both running and widening
from the umbo to the opposite end, which is slightly sinuous. I imagine
these carinal latera occupied a nearly triangular space between the
middle of the three lower sides of the upper latera and the basal
portion of the carina. Rostral latera, rostrum and peduncle
unknown; the rostral latera must have been very narrow.

Affinities.—In
the shape and manner of growth of the scuta, and more especially of the
upper latera, this species is certainly more closely allied to the
eocene S. quadratum, than to any other species; but in the
peculiar characters of the carina, it is nearer to the recent S.
rutilum; we have previously seen that the nearest congener to S.
quadratum is this same S. rutilum.
The most conspicuous diagnostic character of this species is derived
from the peculiar form of the carina,—its tectum being bounded by a
rounded ridge on each side. This square-edged ridge running from the
apex to the baso-lateral angle of the scuta is a trifling, but I
believe, a diagnostic character. If I am right in placing S.
rutilum
in the genus Scalpellum, and I think there can be no doubt of this,
considering the characters of its complemental male, then there can be
no question that the present species belongs to the same genus.

Carina
having intra-parietes, with the tectum slightly angular or
subcarinated, basal margin rectangularly pointed: whole valve more or
less bowed inwards, but with the inner margin nearly straight; tectum,
in a transverse line, more or less convex; surface nearly smooth, with
a few faint longitudinal raised striæ; more or less prominent ridges
separate the tectum, parietes, and intra-parietes from each other.

I
have had far more difficulty in making up my mind regarding this the
commonest cretaceous species, than with all the other fossil
pedunculated cirripedes. From reasons previously stated, I have in this
genus, when only separate valves have been found, taken the carina as
typical. Comparing ordinary specimens of the carina of Scalpellum
maximum and var. sulcatum,
such as those figured in the 'Mineral Conchology,' I should certainly
have considered them quite distinct, had not an examination of Mr.
Fitch's fine collection from Norwich, together with several other
specimens, shown me that there are intermediate forms which it is
scarcely possible to class. Again, had I not seen a particular carina
of S. maximum var. cylindraceum, in which the upper part
displays a different character from the lower in the same individual
valve, I should have unhesitatingly received it as a species, instead
of, as I now do with certainty, as a mere variety. I feel, moreover,
very great doubts whether the S. lineatum be a species, or
merely another variety of S. maximum;

1
For an explanation of this and all other terms, see the remarks on
nomenclature and woodcuts in the Introduction, page 9 and 10.

its
distinctive characters are extremely slight; but they do not blend
away
by any intermediate forms hitherto seen by me. Looking only thus far,
it would have been natural to have classed, without any doubt, all the
carinæ as varieties of S. maximum, but in the same Norwich
beds, from which Mr. Fitch obtained his fine series of carinæ, there
are scuta and terga, which undoubtedly belonged to the genus
Scalpellum, and which, from being of equally large size, nearly equally
numerous, and having a similar state of surface with the above carinæ,
I believe belonged to them: but both the terga and scuta present a
more
remarkable range of variation than do even the carinæ. In the case of
the terga, at one extreme of the series, I did not even at first
recognise the valve to be a tergum! yet the forms so blend together
with very short intervals, that I cannot specifically separate them.
Terga of the two extreme forms come, also, from the same localities in
Scania. In the case of the scuta there are three distinct forms in Mr.
Fitch's collection, which I should certainly have considered as
specifically distinct, had I not been led from studying the carinæ and
terga to believe that this species varies much: moreover, the chief
point of variation in the scuta, namely, in the character of the under
surface of the upper part, I conceive to be, in some degree, in
connection with one chief peculiarity in the terga, namely the varying
prominence of their occludent margins. Although I have not seen any
other instance of so much variation in the scuta: yet I believe that I
have taken the most prudent and correct course in describing them as
mere varieties. From the more frequent coincidence of the carina,
described as that of the true maximum, with the Varieties I
of the scuta and terga, I believe that these valves belonged to the
same individuals: with respect to the two other varieties, I have
hardly any grounds for conjecturing which belonged to which. It is most
unfortunate that not a single specimen of this species seems, hitherto,
to have been found with all, or even a few, of its valves embedded
together.

In giving names to the varieties, as judged of by the Carinæ, there
is a difficulty in nomenclature; for the carina of S. maximum
and of S. maximum, var. sulcatum,
are apparently almost equally numerous in the Norwich beds; and might
either be taken as typical of the species; I have chosen the former
name, simply as having been more commonly used, and from this form
having been apparently most widely distributed. I have described under
it the original carina of Pollicipes maximus of J. Sowerby,
and all the other valves, which I have reason to suppose belonged to
this species. The other carinæ, however, as being in this genus the
typical valve, are described under separate subordinate headings; the
description of S. maximum, var. sulcatum, being
given from Mr. Sowerby's original specimen. Under the typical S.
maximum, I indicate as far as able, to which carinæ the varieties
of the scuta and terga, there described, probably belonged.

Carina, Tab. II, fig. 1. In this,
the typical variety, the carina is very slightly bowed inwards,
widening gradually downwards from the apex, of which no part projected
freely; walls rather thin; tectum very flatly arched, not
sub-carinated; basal margin rectangularly or rather more acutely
pointed; parietes very slightly concave, splaying outwards, narrower
than one side of the tectum, separated from it and from the
intra-parietes by rounded ridges; intra-parietes narrow, not extending
baseward so far as the basal margin of the parietes; width of valve
measured from marginal edge to edge, considerably greater than the
depth, measured in the same place from the central crest to either
marginal edge; but the width compared with the depth varies a little:
inner margin of valve nearly straight. Length of longest specimen (Mus.
Fitch) nearly 1½ inch. This variety in the Norwich beds seems about
equally common with var. sulcatum,
but the former alone is found in Hanover and in Scania, excepting that
in the latter country some specimens indicate a passage to the var. cylindraceum.

Scutum,
Tab. II, fig. 8. In Mr. Fitch's collection there are three left-hand
valves of a Scalpellum, which, from their size and smoothness, I have
no doubt belonged to this species, and from their thinness, probably to
the variety of carina considered as typical under the simple name of S.
maximum:
valve unusually thin and little convex; trapezoidal, with the apex
less
produced than is usual in the genus; broad in proportion to its
length,
the basal margin being .66, and the occludent margin .98 in length,
therefore the breadth equals two thirds of the length. Basal margin
(just perceptibly hollowed out) forming less than a right angle with
the (just perceptibly outwardly arched) occludent margin, and forming
an almost exact rectangle with the lateral margin; the latter meets
the
tergal margin at an angle of about 135°. The edge of the tergal margin
is thickened and slightly reflexed; the upper part of the lateral
margin is in some specimens a little bowed inwards. The baso-lateral
angle is rounded and just perceptibly protuberant; no ridge or furrow
runs from it to the apex. Internally the depression for the adductor
muscle is singularly shallow (fig. 8 c); a very small
portion
of the upper part of the valve projected freely; the internal surface
of the valve, above the pit for the adductor muscle, has not been
thickened, and is therefore slightly concave or almost flat. The
internal occludent edge in the upper part is only a very little
widened, and is flat; on the tergal margin,

a narrow ledge of about equal width with the occludent edge, marked
likewise with lines of growth, must have overlapped the tergum. Largest
specimen 1.15 in length.

Scutum,
Var. II, Tab. II, fig. 9. This valve is narrow, moderately convex, with
the upper portion much acuminated; the tergal margin is somewhat
hollowed out, and is bordered by a narrow smooth slip, (as in the
scutum of S. arcuatum,) which is simply formed by the
thickening from within of the upper part of the valve; this slip does
not reach to the uppermost point. The occludent margin is somewhat
arched, at nearly right angles to the basal margin; lateral margin
forming an angle a very little above a right angle with the basal
margin. A conspicuous, curved, angular ridge runs from the apex to the
baso-lateral angle, (which is not at all protuberant,) and divides the
valve obliquely into two almost equal halves. Surface just perceptibly
striated, finely and longitudinally. Internally there is a deep pit for
the adductor scutorum, which is situate low down in the valve; the
inner occludent edge in the upper part of the valve (b), above
the adductor scutorum, widens suddenly, and is formed into a furrow,
which, however, I do not believe to have had any functional importance; the central internal surface of the valve, above the pit for the
adductor muscle, is somewhat prominent; and a quite small, almost
flat,
portion of the tergal side is marked by lines of growth, showing where
it overlapped the tergum. Altogether there is a considerable
resemblance between this valve, both externally, and more especially
internally, and that of the Pollicipes Angelini. From the
valve being acuminated, with the upper part rather solid, and from the
surface being just perceptibly striated, it more probably belonged to
var. sulcatum than to the typical S. maximum.

Scutum,
Var. III, Tab. II, fig. 10. This third variety, of which the specimen
is a fine large one, is about intermediate in outline or acumination
between the first and second varieties: the tergal margin is thickened
and reflexed as in the first, and is not bordered by a smooth narrow
slip as in the second variety. There is no distinct angular ridge, as
in the second variety, running from the apex to the baso-lateral angle.
Internally the differences are more conspicuous; the depression for
the
adductor muscle is pretty well developed; a large portion of the upper
part of the valve projected freely; the internal occludent edge, above
the adductor-depression, becomes greatly widened and deeply hollowed
out, but yet the furrow I believe, as in Var. II, to be of little or no
functional importance, and merely a consequence of the internal
thickening of the central upper part of the valve; on the tergal side
a
wide ledge shows the extent to which that margin overlapped the tergum.
The internal surface of the valve, above the adductor-depression, is
filled up solid and is exceedingly prominent, as is the ridge extending
from it to the apex; this ridge, from the unusual width of the
internal
occludent edge, is pushed over to the tergal side of the valve.

Professor
Steenstrup has sent me two small scuta, collected by M. Angelin at
Kopinge and Balsberg, in Scania, which come near to the Third variety;
the internal furrow, however, along the occludent margin, is much
narrower, deeper, and oblique, so that it is partly

covered by a lateral projection of the central portion: a tolerably
distinct ridge runs from the apex to the baso-lateral angle. Amongst
the several specimens from Hanover sent me by Drs. Dunker and Roemer,
the scuta all belong to the First variety.

I
believe all these differences in the scuta of the three varieties ensue
partly from the varying acumination of the upper part, and consequently
of the extent to which the apex projected freely, but chiefly from the
degree to which the upper part of the valve above the adductor muscle
has been internally thickened. In the first variety the upper part is
simply concave, and the pit for the adductor very shallow; in the
third
variety, the same upper part is highly prominent, and apparently as a
consequence the internal occludent edge is deeply furrowed; the pit
for
the adductor muscle is deepest in the second variety.

The
above differences would perhaps affect the outline of the terga, but I
am not able to follow the precise manner; nor should I have thought
them sufficient to have produced the amount of variation presently to
be described in the terga; but possibly other scuta may vary still
more. At first I concluded that the upper part of the inner occludent
edge, which in Var. III is deeply furrowed, received in it the
occludent edge of the tergum (as the furrow on the tergal side
of the apex of the scutum receives the edge of the tergum in the recent
Pollicipes mitella),
but this on consideration I do not think can possibly be the case,
although it would amply account for the variation in the terga.

Terga.
I have seen great numbers of these valves; eight specimens are in Mr.
Fitch's collection from Norwich; one is figured by Mr. J. Sowerby in
the 'Min. Conch.,' (Pl. 606, fig. 6,) and they are numerous in the
collection from Scania and Hanover. These valves, which, as stated in
the preliminary remarks, present a most remarkable amount of variation,
will be best described under three distinct heads.

Variety
I. Tab. II, fig. 5. This valve, from its greater width and smoothness,
compared with the other varieties, perhaps belongs to the typical S.
maximum.
Surface smooth, with a mere trace of some longitudinal striæ,
sub-rhomboidal, elongated, with the apex much produced and curled
towards the carina; nearly flat; the occludent margin arched, nearly
equal in length to the scutal margin; upper carinal margin hollowed
out, about half the length of the lower carinal margin; the occludent
and upper carinal margins meet each other at a very small angle, making
the apex almost horn-like; from it to the bluntly pointed basal angle,
a slight rounded ridge, and on the carinal side of it a slight furrow,
(both becoming less plain towards the lower part of the valve,)
extends. As seen internally, the thickness of the valve, in its upper
part, varies; a rather large upper part projects freely. A rim along
the occludent margin is rounded and slightly protuberant, with a slight
depression in the valve parallel to it. Length of the largest specimen
1.2 of an inch.

This variety is found commonly near Norwich, in Scania, and Hanover.

Tergum. Variety
II. Tab. II, fig. 6. The valve in this variety (from near Norwich) is
much elongated, sub-triangular, approaching to crescent-shaped; lines
of growth conspicuous, with a few very faint longitudinal striæ.
Carinal margin not (or

barely)
distinguishable into an upper and lower portion; the whole being
nearly
straight, or very slightly concave. Apex extremely produced, narrow,
and horn-like; curled towards the carina; apparently (for the apex is
broken) a considerable portion was thickened, and must have projected
freely. Occludent margin slightly arched, about equal in length to the
scutal margin, which latter in the lowest part is curved and projects a
little. Basal angle bluntly pointed. A rounded ridge (with a mere trace
of a furrow on its carinal side), almost disappearing in the lower part
of the valve, runs from the apex to the basal angle in a slightly
curved course, strictly parallel to the carinal margin. The rim of the
valve along the occludent margin is rounded and strongly protuberant,
and, parallel to it, the surface is considerably depressed. Length of
valve, when perfect, 1.2 of an inch. This variety differs from the
first in the much greater straightness of the carinal margin, in the
occludent rim being more protuberant, and in the scutal margin not
being quite straight. One specimen presented a decidedly intermediate
form, though rather nearer to the first than to the second variety.

Tergum.
Var. III. Tab. II, fig. 7. The valves of this variety, of which I have
seen five specimens, were for a long time quite unintelligible to me,
and I at first even thought that perhaps they were rostral latera, but
I now find that in outline, though not in general appearance, owing to
their great thickness, they closely resemble the terga of S. magnum.
One of the four specimens is almost exactly intermediate between the
variety last named and that now to be described; hence there can be no
doubt that they are really terga. The chief characteristic of the
valves of this variety is their narrowness, and the solidity of their
upper ends, which, together with a point of structure presently to be
mentioned, makes me think it likely that they belonged to the
individuals which possessed a carina, hereafter to be described under
the name of S. maximum, var. cylindraceum. Valve
smooth but with the lines of growth plain, extremely narrow, almost
crescent-shaped; carinal margin considerably more concave than in Var.
II, with a barely perceptible prominence in the upper part, marking the
commencement of the freely projecting portion, and probably the point
of upward extension of the carina. The occludent margin is arched, and
is equal in length to the straight scutal margin. From the apex there
runs a fine furrow (instead of a ridge and furrow, as in Vars. I and
II,) to the basal angle, nearly parallel to the carinal margin, but
almost blending with it in the lower part of the valve. The upper
freely projecting portion is much thickened, and rendered almost
horn-like, but to a variable extent; owing to this the width of the
valve in the upper part also varies. In the specimens most
characteristic of the present variety, the rim of the valve along the
occludent margin is not at all, or barely, protuberant, nor is there
any plain depression parallel to the occludent margin: in the
intermediate specimen, however, above alluded to, the rim is
protuberant and there is a plain depression, though both much less
conspicuous than in the tergum of Var. II. On the internal surface of
the upper freely projecting part, (marked with lines of growth,) there
can be observed in two specimens a slight and variable longitudinal
depression; judging from what occurs in the recent genus

Lithotrya, and from what may be faintly seen in the tertiary Pollicipes
carinatus, and even in some specimens of P. mitella,
I believe that this structure indicates that the upper freely
projecting portion of the carina had its inside filled up and rendered
prominent, which we shall see is the case with the carina of the
variety cylindraceum. Length of largest specimen, eight
tenths of an inch.

This variety is found at Norwich, in Scania, and at Cyply bei Mons,
in Belgium.

Amongst the Scanian specimens from Kopinge (where the carina of the
true S. maximum
is commonly found) there are some terga differing from the variety just
described, only in having the lower part of the valve less produced;
and more especially in having on the internal surface of the upper part
a smooth prominent ridge, lying rather nearer to the occludent than to
the carinal margin, and therefore in exactly the same position in which
a little group of small, sharp, longitudinal ridges occurs in the terga
of S. arcuatum and of some other species. I am surprised at
such a point being variable, but I cannot doubt that this valve belongs
to the same species. I may add that it was this trifling point of
structure, which first led me to suspect that these singular
crescent-shaped valves were really terga. Finally, I may remark, that
when all the ten terga now described are placed in a row, it is
scarcely possible to doubt that they form merely varieties of the same
species.

Carinal latus, Tab. II, fig. 4. This is
the only valve which remains to be described, for neither the rostrum
nor rostral latera are as yet known. It was found at Kopinge, in
Scania, where the carina of the true S. maximum occurs
abundantly; it was sent to me by Professor Steenstrup, who attributed
it to this species. I have also seen a specimen from Hanover, where the
carina of the true S. maximum is also found, and another
small specimen from Charing, in Kent. Valve thin, of an irregular
shape, sub-triangular; flat, except at the umbo, which projects
outwards, owing to a ledge formed beneath and round it; carinal margin
very slightly convex, with a linear furrow parallel to it, between
which and the edge the lines of growth are abruptly upturned; lower
margin considerably convex; upper margin slightly concave, with a
slight depression parallel to it, between which and the edge the lines
of growth are rectangularly reflexed towards the umbo. The two Scanian
specimens differed slightly in outline; chiefly with respect to the
projection of the ledge round the umbo. Width of largest specimen one
quarter of an inch. This valve unmistakeably resembles the homologous
valves in S. quadratum and fossula, but can be
distinguished from both; the end opposite the umbo is much less
produced than in S. quadratum; the whole valve is wider, and
the furrows much less developed, than in S. fossula, to which
it comes nearest.

Affinities.
Before describing the several varieties as characterised by their
carinæ, I will offer a few remarks on the affinities of this, the most
common and widely distributed species of all the cretaceous
pedunculated cirripedes. Mr. James Sowerby at first naturally described
it as a Pollicipes; quite lately in Mr. Dixon's work he has
considered it as belonging to the same genus with his eocene Xiphidium
quadratum and our Scalpellum

quadratum. Still closer is the affinity with the
cretaceous S. fossula;
the carinæ of both have intra-parietes; the tectum is distinct from
the
parietes, which latter are either channelled or concave; the
trapeziform scuta of S. quadratum, fossula, and maximum,
are unmistakeably alike, and even more striking is the resemblance of
the carinal latera; there can be no doubt of these three species
belonging to the same genus, and having the same number of valves,
namely, as I have shown under S. quadratum and fossula,
probably twelve.

Geological History. This species, with its varieties cylindraceum
and sulcatum,
is very common in the Upper Chalk strata of Norwich; I have seen one
specimen from the Upper Chalk of Northfleet, in Kent. It is common in
the sandstone beds of Scania, which I am assured by Professor
Forchhammer, are without doubt equivalent with the Faxoe beds, and
therefore belonging to a stage above our flinty chalk. I have seen,
also, one specimen, belonging, I believe, to this species, from the
same stage in Westphalia; and another from Belgium; it is also common
at Gehrden, in Hanover, in the 'Oberer Kreidemergel' of Roemer.

Carina,
with the upper portion projecting freely, and with the inside filled up
by the rounded inflected intra-parietes, so as to be almost
cylindrical; exterior surface smooth, with the tectum and parietes
almost confluent.

Amongst the specimens from Norwich, two
differed from the others in being a little more elongated and smoother,
in the parietes becoming almost confluent, low down on the valve, with
the tectum, and in the intra-parietes being very little developed. On
the internal face this variety presents its most remarkable character;
for a large upper portion of the valve must have projected freely, and
the intra-parietes, instead of forming a thin wall on each side, are
thickened, rounded, and turned inwards, so as almost to meet, and thus
to fill up the original concavity of the valve. Hence a section (fig.
2, c) of the upper part, some way below the apex, is almost
cylindrical, or more strictly oval with the longer axis in the
longitudinal plane of the animal, with either a wedge-formed hollow, or
a mere, almost closed, cleft on the under side, penetrating not quite
to the centre of the solid valve. The two specimens differ, one in
being in a transverse line exteriorly much depressed, the other highly
arched or convex, and internally still more conspicuously in the degree
to which the intra-parietes have filled up the upper part. In one of
the specimens there is even a difference on the opposite sides of the
same individual valve. Notwithstanding these varieties, I should have
much hesitated to have ranked

these peculiar carinæ under S. maximum, had not the upper
part in one specimen actually retained all the usual characters of S.
maximum, the precise line where the manner of growth had changed,
being distinctly visible. It is represented in Plate II, fig. 2, a
and b. Amongst the Scanian specimens, some make an approach
to this variety.

Carina considerably bowed
inwards, subcarinated; width of valve about half of the depth; tectum
in a transverse line, steeply arched; parietes and intra-parietes
rather wide; apex filled up solid, and projecting freely a little;
exterior surface with a few rounded striæ on either one or both sides
of the two ridges which separate the tectum and parietes.

Having
had the advantage of seeing Mr. J. Sowerby's original specimen, the
valve now to be described is certainly that figured by him as Pollicipes
sulcatus. As already stated, certain specimens of this variety
differ strikingly from the carinæ typical of S. maximum;
whereas others, from the same formation and locality, are so
intermediate that they can, with difficulty, be arranged on either
side: this is also the case with one from Cyply bei Mons, in Belgium.
This variety is common in the Upper Chalk of Norwich.

In a well-marked specimen of this variety, the chief distinctive
characters, as contrasted with the true S. maximum,
consist in the tectum being more steeply arched, in the depth of the
valve being much greater than the width, in the intra-parietes and
parietes being more developed, in the whole valve being more bowed
inwards, in the walls being thicker and apex filled up solid, in the
surface having a few fine raised lines on each side of the ridge
separating the tectum and parietes, and, lastly, in the tectum being
sub-carinated.

1 If I am correct in considering the
carina of P. sulcatus to be only a variety of that of S.
maximum, the tergum figured by Mr. Sowerby as belonging to his P.
sulcatus cannot so belong; for it does not at all resemble the
homologous valve of S. maximum.
I believe from the character of the ridge running from the apex to the
basal angle, that it belonged to a Pollicipes, which must have been
coarsely striated longitudinally, and therefore I have provisionally
described it under Pollicipes striatus.

Carina moderately bowed inwards, widening gradually
downwards from the apex, of which a small portion is filled up solid,
and must have projected freely; walls moderately thick; the two sides
of the tectum are rather steeply inclined to each other, and meet in a
central line, which is subcarinated with a slightly prominent ridge;
basal margin rectangularly pointed; parietes nearly flat, about as
wide
as the tecta, in some specimens perpendicular, so as not to be visible
when the valve is viewed from a central dorsal point; in others, very
steeply splayed outwards; separated from the intra-parietes by a
conspicuous rounded ridge, and from the tectum by a nearly equally
large ridge, which has generally one, two, or three fine, longitudinal,
raised lines on either one or both sides of it: in one specimen the
whole surface was thus coarsely and obscurely lined. The intra-parietes
are rather wide, extending to the basal margin of the parietes. Depth
of valve, measured from the central crest to either inner edge, is
about equal to the entire width, as measured from inner edge to edge.
The depth compared with the width, though the most conspicuous
character, varies a little. Inner edge of valve nearly straight. Length
of longest specimen (in Mus. Bowerbank) 1.6 of an inch. This
is the largest carina I have seen in any fossil cirripede.

Carina with the whole
exterior surface covered with fine, rounded, longitudinal lines,
scarcely visible to the naked eye; with a thicker ridge on the central
crest, and with two or three similar ones separating the tectum and
parietes; width of valve about half of depth; subcarinated;
inter-parietes rather wide, not separated by a conspicuous ridge from
the parietes. Apex filled up, solid, and projecting freely a little.

Lower Chalk of Sussex, Mus.
J. Morris; Mus. J.
Sowerby.

I
have seen two carinæ in the collections of Mr. Morris and Mr. J.
Sowerby so exactly like each other, and having a somewhat different
aspect from S. maximum, var. sulcatum, to which
they
come nearest, that they deserve to be described, whether or not they
are really specifically distinct. I long hesitated whether to give them
a specific name, and have been, in some degree, influenced in doing so,
from the presence of scuta and terga in the Lower Chalk, which indicate
a distinct but closely-allied species. The scutum is in Mr. Morris's
collection, and came in the same lot with the carina from Sussex: the
tergum

is
in Mr. Bowerbank's collection from the Lower Chalk of Maidstone. These
valves are marked with longitudinal raised striæ more plainly than is
the carina.

Carina (fig. 12);
moderately bowed inwards; inner margin nearly straight; widening very
gradually downwards from the apex, of which a very small part is filled
up solid, and must have projected freely; walls rather thin. Both
tecta
and parietes are regularly striated longitudinally, with raised,
hair-like, fine lines scarcely visible to the naked eye; one central,
and two or three on each side between the tectum and parietes, being
about twice as large as the others, and visible to the naked eye. Tecta
rather steeply inclined towards each other; central line sub-carinated; basal margin rectangularly pointed; parietes slightly concave, about
as
wide as half the tectum; steeply inclined outwards; separated from
the
intra-parietes on each side by a slight ridge. Intra-parietes set a
little inwards, wider in the widest part than the adjoining parietes or
tecta; extending baseward not as far as the basal margin of the
parietes. Depth of valve measured from central crest to either inner
edge, nearly equal to the entire width, as measured across from inner
edge to edge. In many respects this carina is intermediate between
those described under S. maximum and S. maximum,
var. sulcatum;
but comes nearest to the latter: the intra-parietes not extending
so
far baseward; and the delicately lineated exterior surface gives it,
however, a somewhat different aspect.

Scutum (fig. 11); this valve, from the Lower Chalk of
Sussex, resembles that of S. arcuatum; its surface is
covered
with raised striæ, which are further apart, and less plain than in the
typical specimens of S. arcuatum
from the Gault, but resemble those in the variety from the Grey Chalk
of Dover. Outline trapezoidal: the baso-lateral angle is very broad,
rounded, and protuberant; no ridge runs from it to the apex: the
basal
margin projects very slightly close to the rostral angle, and the
tergal margin is not inflected as in S. arcuatum. The
internal surface of the valve, along the tergal margin, is not furrowed
or marked by lines of growth: I have no doubt that this valve is, at
least, distinct from S. arcuatum.

Tergum. This valve, from the Lower Chalk of Maidstone,
resembles that of S. arcuatum,
var. from the Grey Chalk; it is, however, slightly more elongated: it
further closely resembles a tergum, which I have provisionally
attributed to Pollicipes striatus, differing from it in being less
elongated, and more especially in the absence of a ridge, steep on the
carinal side, which in that species runs from the apex to the basal
angle.

Finally, I may remark, that these three valves, on
the supposition that they have been rightly attributed to one species,
indicate a form intermediate between Scalpellum maximum of
the Upper Chalk, and S. arcuatum of the Grey Chalk and Gault.

Carina
smooth, narrow, furnished with intra-parietes, widening gradually from
the apex downwards; extremely much arcuated, so that the uppermost
part, of which none, or very little, projected freely, is at right
angles to the basal part. Not only is the dorsal surface considerably
arcuated, but so are the inner margins, which is much more important.
Basal margin sharply pointed, with the two edges meeting each other at
about an angle of 75°. Roof with the two sides continuously and flatly
arched; parietes rather narrow, slightly concave, barely separated
from
the tecta: the concavity of the parietes, as seen on the basal margin,
together with the sharpness of the central portion, makes the lower
part of the valve spear-shaped. The intra-parietes are set a little
within the parietes; they extend down to about two thirds of the
entire
length of the carina, and not to the basal margin of the parietes:
they
are widest at about only one fourth of the entire length of the carina
from the apex, and here they equal in width the rest of the valve.
Internally the valve is, in the upper part, owing to the wide
intra-parietes, deeply concave; in the lower part, only slightly so.

Length of carina, measured along the chord of the arch, .75 of an
inch.

Affinities. This species certainly comes very near to S.
maximum;
but I think it is distinct, and is its representative in the Grey
Chalk. I have seen only a single specimen. The carina differs from the
former varieties and species in its smoothness, thinness, in the
acumination of the basal margin, in its much arcuated form, and more
especially (for this, probably, would greatly influence the outline of
the terga,) in the inner margins being also thus arcuated.

Carina
narrow, much bowed inwards; tectum apparently separated from the
rectangularly-inflected parietes by a ridge; the intra-parietes extend
down half the valve, and are there obliquely and abruptly truncated;
basal margin sharply pointed.

Chalk.

I
know this species only from the plate in Mr. Dixon's work. Being well
aware of Mr. J. de C. Sowerby's great accuracy, I cannot doubt that the
intra-parietes are at their lower end, abruptly and obliquely truncated
in the manner represented in the Plate: this character, with its
sharply-pointed basal margin, makes me believe this species to be new:
it comes, I imagine, nearest to S. hastatum.1

Carina (fig. 5, a-d);
moderately arched, narrow, gradually widening from the apex to the
base, plainly marked by lines of growth: no part apparently projected
freely. The tectum is flatly arched, sub-carinated, with its central
crest forming a rounded protuberant ridge; on each side, the tectum is
bounded by similar, very slightly larger ridges, making

Carina having
apparently wide intra-parietes; tectum in a transverse line, flat and
smooth, bordered on each side by a prominent ridge; basal margin
abruptly truncated.

Bohemia. Untern Plänerkalke
(Chalk-marl).

I
know this species only from an imperfect plate, but good description of
a carina, in Reuss' work: it is an interesting form, showing in its
truncated basal margin and flat tectum a still closer affinity to the
recent S. rutilum, even than does S. fossula; thus
confirming the
view
I have taken of the affinities of these several species.

together
three ridges. The basal margin is bluntly pointed, with the two sides
meeting each other at an angle of rather above 90°. Parietes rather
narrow, rectangularly inflected, slightly concave: in the upper part
there is no trace of intra-parietes.

Terga (fig. 5, e-i).
In Mr. Flower's collection there is a tergum, (embedded in exactly the
same matrix,) which, from a certain degree of resemblance in outline
with that of S. arcuatum, the nearest congener to S.
trilineatum, and from another point of resemblance with S.
fossula, I believe belonged to this species.1
The valve is very smooth, with obscure traces of fine striæ radiating
from the umbo; nearly flat; pointed oval, but with the scutal side
much
more protuberant than the carinal. Apex much acuminated, curled
forwards; carinal margin much and regularly bowed from the upper to
the
basal point, which latter is blunt and square: from it to the apex
there runs, in a curved line, nearly parallel to the carinal margin, a
barely perceptible broad ridge. Occludent margin curved up towards the
umbo, short compared to the scutal margin; parallel to it there runs a
very wide and very shallow depression. Scutal margin, with a portion
corresponding with the above depression, forming rather more than a
third of the margin, not projecting so much as the lower two thirds,
and separated from this lower part by a slight bend, probably marking
the spot to which the apex of the upper latera extended.

Affinities. The carina obviously most resembles that of S.
fossula and arcuatum;
it differs plainly from both, in having a central rounded ridge: in
the
two well-developed boundary ridges of the tectum it comes nearest to
the cretaceous S. fossula; but in the absence of the
intra-parietes (and this I conceive is a more important character), it
comes nearest to the S. arcuatum,
from which, however, it can be at once distinguished by the absence of
the longitudinal striæ. The tergum above described, which I believe
belonged to this species, in the form of the scutal margin, comes
nearest to that of S. fossula, though in general shape
perhaps nearer to S. arcuatum. In S. fossula the
carina has intraparietes, which are closely adjusted to the straight
carinal margins of the terga: in S. trilineatum
the intra-parietes are absent, but in their place the carinal margins
of the two terga are themselves highly protuberant, so that in these
two species, although the upper parts of the carinæ and terga are
separately of very different shapes, they give, when combined together,
a similar general outline.

1 It must
however be added that the terga, at present unknown, of S. hastatum,
a
species occurring in the Grey Chalk of Dover, would probably have the
same outline, and almost certainly would have a very smooth surface.

I
know this species only from a single carina, which is chiefly
characterised by its simplicity: it is, I think, certainly distinct
from all the others. In the sides of the carina being simple, that is
in not being divided by a ridge into parietes and intra-parietes, it
comes nearest to S. arcuatum and trilineatum, from
the former of which it is readily distinguished by its smoothness; and
from S. trilineatum
by the absence of the three ridges. This species possesses some
interest, as being the oldest cirripede, which I have ventured to
attribute to the genus Scalpellum. Carina moderately
tapering, slightly bowed towards the terga; sub-carinated, but with
the
central ridge smooth; transversely moderately arched; basal margin
rectangularly pointed; the whole surface is smooth. Parietes extremely
narrow, rectangularly inflected, set inwards, not extending down to the
basal margin, with the lines of growth almost parallel to the inner
edges of the valve.

I
have ranked this species under Scalpellum instead of Pollicipes, from
the somewhat greater resemblance of its scuta and carina with the
fossil species of Scalpellum, than with any known Pollicipes; though
in
some respects it appears rather intermediate. This species appears to
come nearest to the Pollicipes radiatus of J. de C. Sowerby
in 'Geol. Trans.,' vol. iv, 2d Series, Pl. XI, fig. 6, but besides
that
that species comes from the Lower greensand, the lower angle of its
tergum is much more pointed; the upper figure of the two there given
appears to be something wholly different. From the state of the
specimens, I believe that the three following valves, all in Mr.
Bowerbank's collection, belonged to the same species.

General Appearance.
Carina, scuta, and terga plainly marked with prominent, very narrow,
straight ridges, radiating from their apices; the interspaces between
these ridges are

three or four times as wide as the ridges themselves; the lines of
growth are very fine and narrow.

Carina (fig. 7, a, b, g);
narrow, considerably arched: tectum flatly arched, obscurely
subcarinated: parietes rectangularly inflected, somewhat concave, and not
longitudinally ridged,
like the tectum, about two thirds as wide as half the tectum: basal
margin bluntly pointed, the two edges meeting each other at rather
above a right-angle; a trace of a rounded ridge separates the tectum
and parietes; in the upper part of the carina there is no trace of
intra-parietes, therefore the section of the upper half of the carina
is only four-sided, see fig. 7, g.

Scutum (fig. 7, f);
moderately convex, with the apex acuminated: lateral margin nearly
parallel to the slightly arched occludent margin, and at right angles
to the straight basal margin; a distinct ridge runs from the apex to
the baso-lateral angle, which is distinctly prominent and rather sharp.
The valve, above a line running from the apex to the tergo-lateral
angle, is inflected; and the narrow portion thus inflected, which
cannot be seen when the valve is viewed from above, is destitute of the
longitudinal ridges.

In a specimen from the Grey Chalk of
Dover, in which the internal surface was visible, there was, above the
well-marked depression for the adductor muscle, a prominent, central,
slightly oblique ridge, with the inner occludent edge of the valve
widened and slightly hollowed out on the one side, and with a trace of
a furrow on the other or tergal side.

Terga (fig. 7, c, d);
flat, oval, with the scutal angle rather protuberant; basal angle not
sharply pointed, from it to the apex there runs an obscure furrow,
which furrow in the lower part of the valve is central, but higher up
is situated at about one third of the width of the widest part of the
valve from the carinal margin; in the lower part of the valve, the
lines of growth (and consequently the margins of the valve) make with
this furrow, equal angles on its opposite sides. The valve is slightly
depressed, parallel to the occludent margin. A small portion of the
apex projected freely; internally, in the upper part, rather
nearer to the occludent than to the carinal margin, the valve is
prominent, and this part is marked with two or three little ridges (c)
ending abruptly downwards.

Size
of largest specimen,—length of carina, .85 of an inch; of scutum, from
the apex to the basal margin, rather above .6; of terga, .55. I do
not,
however, know that these valves belonged to the same individual.

Variety.
In the British Museum there is a scutum, and in Mr. Flower's collection
there is a tergum, both from the Grey Chalk of Dover, which are most
closely allied to, if not identical with, the above valve. The raised
striæ on both are rather further apart and are less prominent. In all
the other characters the scutum is identical. The tergum differs in its
carinal margin, being rather more angularly bent, and in there being no
furrow running from the apex to the basal angle; but these differences
are trifling and insufficient for distinguishing a species. Amongst
some specimens most kindly sent me by Roemer, there is a tergum from
the Pläner of Sarstedt (Chalk-marl), which is identical with this.

Valves with rather wide
elevated lines radiating from their apices. Carina, with the upper part
freely projecting, and internally urnished with a central prominent,
longitudinal crest.

Scania (Kjuge). Mus. Univers.
Copenhagen.

Professor
Steenstrup has described under this name some carinæ, in so worn a
condition, that I confess that I thought it quite impossible to
characterise them; and under the name of P. undulatus, some
well-preserved terga. Quite lately, M. Angelin
has sent to Professor Steenstrup, from Kjuge in Scania, several of the
same carinæ in a much better condition, a scutum, and some broken terga
of P. undulatus, which, from the similarity of their
longitudinally striated surfaces, M. Angelin
believes belonged to the same species: I quite concur in the
probability of this view. The better state of the carinæ proves the
sagacity of Professor Steenstrup, in considering his worn specimens
indicative of a distinct species. Had I seen these carinæ alone, I
should have much hesitated in considering them as belonging to a
Scalpellum: for they differ considerably from the same valve in all
other species; the parietes, or rather the part answering to the
parietes, being here so much inflected, that they fill up and render
solid the upper part of the valve; but the scutum undoubtedly belonged
to a Scalpellum, and the terga closely resemble the same valve in the S.
arcuatum.

Carina (fig. 8, b, c, d); narrow, elongated, strong and solid; moderately bowed inwards; basal
margin rectangularly pointed; surface covered with rather broad slight
ribs, central one being apparently (for the best specimens are much
worn) twice as broad as any of the others. In a transverse line, the
tectum is considerably arched in the upper part of the valve, and only
slightly arched in the lower part. A considerable length of the upper
part must have projected freely; this portion being filled up solid,
and having a central, largely prominent crest or ridge: it appears,
for
the specimens are in a much worn condition, as if the ridge had been
formed by the inflection of the parieties on each side, and their
perfect junction. In the peculiar and almost monstrous variety of S.
maximum, called var. cylindraceum, we have nearly the
same structure;
a
cleft, however, being left, marking the line of junction of the
opposite parietes. In general appearance and proportions, this carina
comes nearest to those of Scalpellum; but in the peculiar modification
of the parietes (if they can be so called) into a central crest, and in
the apparent (from worn state) absence of any distinct ridge
separating the tectum and parietes, the valve departs from the general
description of the carina in Scalpellum.

Scutum;
of this valve, which undoubtedly belonged to a Scalpellum, there is one
entire specimen, but with the angles so much rounded, that I can point
out no distinguishing character from the same valve in S. arcuatum
(fig. 7, g), of which a figure has been given, except that
the
longitudinal ridges are proportionally broader and further apart. The
ridges closely resemble those on the above-described carina.

Terga
(fig. 8, a); sub-triangular, flat, strong, and thick, with
moderately
wide, not quite straight ridges, radiating from the apex: the
interspaces between the ridges are three or four times as wide as the
ridges themselves; valve very slightly depressed, parallel to the
occludent margin. A slight ridge, connecting the sharp basal apex, runs
quite close to the carinal margin, even in the lower part of the valve
:
in

Valves, with fine, tuberculated,
elevated lines, radiating from their apices: carina, with the roof in
a
transverse line, gently arched, and with the parietes striated:
scutum,
with the umbo placed nearly in the middle of the occludent margin, with
two ridges running from the umbo to the baso-lateral angle and to the
middle of the basal margin.

Chalk Detritus. Charing, Kent. Mus.
Harris.

Through
the kindness of Mr. Harris, I have examined several valves, which I
believe to belong to the same species: the specimens were found in the
chalk detritus, and, therefore, may have come from the Upper or Lower
Chalk or Chalk-marl; but more probably from the Upper Chalk. With
respect to the scuta and terga I have scarcely any doubt, from certain
peculiarities, that they belonged to the same species; but with regard
to the most important valve, the carina, I cannot feel quite so
certain: when the latter is so held, that the parietes are not
visible,
it has a very close general resemblance to the same valve in Pollicipes
rigidus. In the carina, the present species comes closer to S.
arcuatum
than to any other species; in the other valves, especially in the
singular scuta, it departs widely from that and all other known fossil
forms, with the exception of S. (?) cretæ, of
Denmark. All the specimens which I have seen are small; the carina
being .2 long, and the terga less than .15 of an inch in length, in the
largest specimens.

consequence of this,
the lines of growth make a different angle, on the opposite sides, with
this ridge: as the valve has been somewhat worn, it is possible that
the carinal margin may have been more abraded than is apparent.
Internally, it is seen that a considerable portion of the upper part of
the valve projected freely; beneath this, the inner surface is
slightly
convex, but smooth, and though the shell has been much worn, I doubt
whether there ever existed ridges, as on the internal surface of the
upper part of the terga in S. arcuatum, to which valve this
presents a close general resemblance. Length of tergum (when perfect),
1.2 of an inch.

Carinal Latus (fig. 8, e, f); amongst the fossils from Kopinge (at which place the same species are
found as at Kjuge), there is a valve, which I believe to be a carinal
latus of a Scalpellum, and which, from its longitudinal ridges, more
probably belonged to the present than to any other species: from its
peculiarity it is in any case worthy of description. In form it is a
segment, somewhat less than a quarter, of a circle; of this segment,
nearly half (I believe the upper half) had its end or circumferential
margin much hollowed out, and its surface smooth: the other half has
its periodical growth-ridges very prominent, and these are crossed by a
few slight longitudinal ridges. One of the lateral sides (the upper, I
believe,) is reflexed so as to form a prominent ledge; the other side
is slightly inflected.

The valves
all have their surfaces plainly ribbed longitudinally; the ribs are
narrow, and as they cross each zone of periodical growth they are
tuberculated.

Carina (fig. 10, b, c);
narrow, tapering, little bowed inwards; tectum in a transverse line,
steeply arched, not carinated; basal margin bluntly pointed; in very
young specimens, however, it is evident from the lines of growth, that
the basal margin must have been rounded; the parietes are inflected,
and rather narrow, being barely half the width of half the tectum;
they
are plainly marked by parallel lines of growth; internally the valve
is
rather deeply concave; no part of the apex projected freely.

Scuta (fig. 10, e);
umbo of growth on the occludent margin, at about one third of the
entire length of the valve from the apex; somewhat convex;
four-sided,
the margins consisting of the lateral, which is considerably longer
than the other sides; the basal which forms nearly a right angle with
the lower half of the occludent margin; and of an upper and lower
occludent margin, meeting each other at about an angle of 135°: the
margin which I have here called the upper occludent, homologically
corresponds with the tergal margin of the other cretaceous species, and
with the upper, nearly straight, portion of the occludent margin in the
tertiary S. magnum and the recent S. vulgare,—a
fact
which has been mentioned under the head of Scalpellum. The edge of the
upper occludent margin forms a strongly prominent ridge, with its apex
forming a slight projection; a second less prominent ridge runs from
the umbo to the baso-lateral angle, and a third faint ridge runs from
the umbo to a point in the basal margin, nearer to the rostral than to
the baso-lateral angle. Internally there is a rather deep hollow for
the adductor muscle; along the under surface of the upper occludent
margin there is a slightly prominent ridge, bordered by two slight
depressions.

Terga (fig. 10, a); flat,
elongated diamond-shape; close and parallel to the occludent margin
there is a narrow, very prominent ridge or plait, the end of which
forms a slight projection; a straight ridge runs from the apex to the
sharp basal angle; the scutal and lower carinal margins are of equal
length, and longer than the occludent and upper carinal margins, which
latter are equal, and meet at an angle very slightly less than a
rectangle. On the under surface there is a slight depression and ridge,
close and parallel to the occludent margin. I have no doubt that the
ridge along the upper occludent margin of the scuta, and that on the
occludent margin of the terga, together with their projecting points,
are related to each other, owing to the close contact of these valves.1

Valves smooth, extremely thin: scutum
with the umbo placed nearly in the middle of the occludent margin, with
three obscure ridges running from the umbo to the tergo-lateral and
baso-lateral angles, and to the middle of the basal margin: carina
with
the apex and basal margin sharply pointed; without distinct parietes.

Preliminary Remarks.
I owe to the kindness of Professor Steenstrup, as in so many former
instances, an examination of several specimens of this fossil, which is
of interest, as being extremely common and characteristic of the white
chalk of Denmark. Amongst the numerous minute specimens from the chalk
detritus of Charing in Kent, sent me by Mr. Harris, there are some
carinæ so similar that I have ventured, with doubt, to rank this as a
British species; the carina, however, in this species, are far from
characteristic. I have felt much hesitation in admitting this species
in the genus Scalpellum: Professor Steenstrup was originally inclined
to believe that the capitulum was formed of only five valves; could
this be proved, the species would very naturally rank with a small
recent one from the Island of Madeira, which, owing to the upward
growth of the scuta, and to certain peculiarities in the animal's body,
I have felt myself compelled to raise to the rank of a genus, under the
name of Oxynaspis. But as the valves of S. (?) cretæ
have never been found united, and as the main ones are very small,
fragile, and generally in a broken condition, the small lower ones
might easily be overlooked. I have seen, indeed, in two instances,

the
middle of the basal margin; the surface between the latter ridge and
the occludent margin covered with fine longitudinal elevated lines.

Scania (Kopinge). Mus.
Univers.,
Copenhagen.

I
have in this one instance departed from my rule of never naming any
other valve, except the carina in the genus Scalpellum; but the scutum
here to be described almost certainly belongs to this genus, and is
interesting in connection with the homologous valves in S.
tuberculatum
and S. (?) cretæ, to which species it is apparently
allied, but yet
differs greatly from them in the umbo being seated at the uppermost
point of the valve.

Scutum, moderately
elongated, slightly convex; a narrow, prominent, well-defined ridge
runs from the apex to the baso-lateral angle, at which point it forms a
narrow projection: a second ridge, not quite so prominent, runs from
the apex to the basal margin, to a point rather nearer to the
baso-lateral than to the rostral angle. That part of the valve between
this second ridge and the occludent margin has four or five faint
longitudinal ridges, whereas the rest of the valve is smooth.
Internally there is a deep depression for the adductor muscle, above
which the surface is simply concave up to the apex.

what
appeared to be upper latera, but as I could not remove them so as to
examine their under sides, I am far from sure that they were not
broken, angular portions of scuta. If we look to the character of the
separate valves, there is a striking and important resemblance between
the scuta of S. cretæ and tuberculatum, in the umbo
being seated in a nearly middle point of the occludent margin, and
likewise in the two ridges running from the umbo to the baso-lateral
angle, and to a central point of the basal margin; in which latter
character of the ridges, this species also agrees with S.
semiporcatum.
These facts have determined me, provisionally, to rank the present
species under Scalpellum. But on the other hand, if we look to the
carina, which, according to our rule, is considered the characteristic
valve in this genus, it rather resembles the homologous valve in
Pollicipes; for the carina has not any parietes separated from the
tectum by a distinct ridge. The terga seldom afford any serviceable
generic characters; but as far as they go, they also rather resemble
the terga in Pollicipes than in Scalpellum. Hence, it is obvious, that
the generic position of S. (?) cretæ is at present
very uncertain.

Valves small, smooth, extremely thin and brittle.

Scutum (fig. 11, c);
trapezoidal, with the upper part of the valve produced into a sharp
point, and with the rostral angle slightly and obliquely cut off. Umbo
seated at a little above the middle of the occludent margin, which is
straight. The tergal margin is longer than the lateral margin: the
basal margin (on the carinal side of the truncated rostral end) forms a
right angle both with the lateral and occludent margins. Valve somewhat
convex near to the umbo, whence three obscure ridges radiate,—one to
the angle between the tergal and lateral margins; a second to the
baso-lateral angle, and a third to the bend in the basal margin; these
ridges, however, seem to vary in strength, and in the largest specimens
could hardly be distinguished: in most of the specimens, the narrow
portion of the valve, which ends in the truncated rostral angle, is a
little inflected. The lines of growth follow the basal and
tergo-lateral margins, and can be traced just bending round the sharp
apex, so that a very narrow ledge is added along the upper part of the
occludent margin.

Tergum (fig. 21, a);
sub-rhomboidal, nearly flat: the carinal margin consists of an upper
larger portion, and of a lower, shorter portion: the occludent and
scutal margins are nearly equal in length. The apex is a little curled
towards the scuta, and is sharp; basal angle bluntly pointed. A faint
curved ridge runs from the apex to the basal angle, at about one fourth
of the entire width of the valve from the carinal margin.

The Carina (fig. 11, b)
widens rapidly downwards from the extremely sharp apex; basal margin
spear-shaped, sharply pointed, the two edges meeting each other at
about an angle of 75°; exterior surface sub-carinated; in a
transverse
line the valve is slightly arched, and longitudinally, very slightly
bowed inwards: with a lens, traces of longitudinal striæ are visible.

Dimensions.
The species seems to have been always small: the largest scutum and
tergum were each about a quarter of an inch in length. Probably the
individuals were attached in groups to corallines at the bottom of the
cretaceous sea.

Valves
from eighteen to above one hundred in number. Latera of the lower whorl
numerous, with their lines of growth directed downwards. Sub-rostrum
always present. Peduncle squamiferous.

CHARACTERS OF THE VALVES IN FOSSIL
SPECIES.

Carina;
widening considerably from the apex, which projects freely, to the
basal margin; parietes not distinctly separated from the tectum;
lines
of growth on the parietes but little oblique. Scuta generally
somewhat massive, convex, sub-trigonal, with

1 This
is one of the rare cases in which, after much deliberation and with the
advice of several distinguished naturalists, I have departed from the
rules of the British Association; for it will be seen that Mitella
of
Oken, and Ramphidiona of Schumacher, are both prior to Pollicipes
of
Leach; yet as the latter name is universally adopted throughout Europe
and North America, and has been extensively used in geological works,
it has appeared to me to be as useless as hopeless to attempt any
change. It may be observed that the genus Pollicipes was
originally
proposed by Sir John Hill (' History of Animals,' vol. iii, p. 170), in
1752, but as this was before the discovery of the binomial system, by
the Rules it is absolutely excluded as of any authority. In my opinion,
under all these circumstances, it would be mere pedantry to go back to
Oken's 'Lehrbuch der Naturgesch.' for the name Mitella,—a
work little
known, and displaying entire ignorance regarding the Cirripedia.

the tergo-lateral margin more or less protuberant, but not divided
by an angle into two distinct margins.

† Scuta smooth, or marked only with fine lines of growth.

A. Scuta without any ridge proceeding from the apex to a
nearly middle point of the basal margin.

B. Scuta with a ridge, sometimes faint, proceeding from the
apex to a nearly middle point of the basal margin.

††. Scuta either longitudinally or transversely (that is in the
direction of the lines of growth) ridged.

As
with Scalpellum, the first of the above two paragraphs contains the
true generic description, as applicable to recent and fossil species;
the second paragraph has been drawn up as an aid in classifying
separated valves. This, the most ancient genus of the Lepadidæ, seems
also to be the stem of the genealogical tree; for Pollicipes leads,
with hardly a break, by some of its species into Scalpellum
villosum; and Scalpellum leads by Oxynaspis into Lepas and the
allied genera: Pollicipes mitella,
moreover, is nearer allied to the Sessile Cirripedes than is any other
Pedunculated cirripede, except, perhaps, Lithotrya, which is also
closely connected with Pollicipes. The six recent species of Pollicipes
might be divided into three sub-genera: one containing the P.
mitella; a second, P. cornucopia, elegans and
polymerus;
and the third, P. spinosus and serta (nov. spec.)
Of the fossil species some, as P. carinatus, dorsatus,
validus,
&c., are related to the first section; others, as P. reflexus
and concinnus, to the second section; and lastly, others, as
P.
glaber and unguis, perhaps form a distinct section,
though more related to P. mitella
than to other recent species. As, however, most species are known by
only a few of their valves, it is scarcely possible to speak with
certainty regarding their finer affinities.

Description:
as in the case of Scalpellum, the following remarks are confined to the
fossil species of the genus. In all full-grown recent species the
number of valves in the capitulum is very large: this seems to have
been the case with the Oolitic P. concinnus, and probably
with most other species, but whether with all may be doubted; from the
size of the carinal latera of the lower whorl in P. unguis, I
suspect that the total number of its valves cannot have been great. The
valves are either smooth or plainly marked by the lines of growth, or
they rarely have longitudinal ridges, or transverse ridges
corresponding to each periodical zone of growth: no recent Pollicipes
has a surface of this latter kind. The valves in Pollicipes are often
strong and massive, with their apices projecting freely from the
capitulum.

Scuta generally three-sided, but
sometimes, from either the baso-lateral or rostral angles being
truncated, there is an additional lower side. The tergo-lateral margin
is either straight or generally more or less convex, but it is never
(as far as I know) divided into two distinct margins, as is always the
case with Scalpellum owing to the abrupt ending of the upturned lines
of growth. The basal margin is either straight or formed

of
two lines meeting each other at a wide angle, or somewhat irregular.
The angle which this basal margin makes with the occludent margin
varies much. The occludent margin is slightly arched, and is sometimes
exteriorly strengthened by a ledge or rim. A prominent ridge runs in
several species from the apex of the valve to the baso-lateral angle;
and in another set of species there is a second obscurer ridge running
to a nearly middle point of the basal margin: in this latter set, the
two ridges no doubt mark the extent to which the rostrum and upper
latera overlapped the scutum. Internally there is almost always a deep
pit for the adductor scutorum muscle: the upper part of the valve
generally projects freely, and is internally marked by lines of growth; sometimes there is a furrow along the upper part either of the
occludent or the tergal margin; in the latter case the furrow seems to
receive the scuto-occludent angle of the adjoining tergum, and thus
locks the two valves together, as in the recent P. mitella.
In two species the occludent margin at the rostral angle is internally
produced downwards into a depending tooth or projection.

Terga:
nearly flat, rhomboidal or sub-rhomboidal; a line formed by the
converging zones of growth, or a ridge, sometimes steep only on the
carinal side, sometimes steep on both sides, runs from the apex to the
basal angle. The basal angle is sometimes truncated.

Carina:
is either bowed inwards or is straight: it widens from the apex
downwards more rapidly than in Scalpellum; generally a considerable
upper portion projects freely; this upper portion is always much less
concave than the lower part: it is sometimes filled up flat, and
sometimes has even a central prominent crest; the basal margin is
either bluntly pointed, rounded, or truncated; the parietes are
generally more or less inflected, but they are not separated by any
defined ridge or angle from the roof or tectum; the lines of growth on
the parietes are transverse, or generally only slightly oblique. These
characters will, I believe, in nearly all cases serve to distinguish
the carina of a Pollicipes from that of a Scalpellum.

Sub-carina: I know of the existence of this valve only in P.
concinnus,
but I cannot doubt that it existed in all, or nearly all, the species.
I have sometimes suspected that it might possibly have been absent in P.
unguis and glaber, in which the carinal latera are so
large.

Rostrum and sub-rostrum: as these valves occur
in
P. unguis, I have little doubt that they are universal; they
are apparently present in P. concinnus; the rostrum
always resembles the carina, but is shorter and proportionally broader; a larger proportion, also, seems always to have projected freely,
caused no doubt by the more abrupt flexure of this end of the
capitulum: this latter character is the most certain one by which the
rostrum may be distinguished from the carina. The sub-rostrum
in P. unguis resembles the rostrum, but is smaller, and
exteriorly is not carinated.

Upper latera: I know these only in P. unguis and
glaber,
in which they consist of a flat triangular plate, and in P.
concinnus, in which they seem to be diamond-shaped. Lower
latera, these in P. concinnus also seem to be
diamond-shaped, as in P. cornucopia; in P. unguis
and glaber the apices of these little valves do not project
freely, and they

have
a different appearance from their homologues in any recent species:
they are trigonal, with their basal margin rounded and one end
produced, to which end a narrow well defined ridge runs obliquely from
the apex of the valve.

The peduncle is known only in P. concinnus; in this
species it is covered with minute quadrangular calcified scales.

Scuta,
almost square, with the basal margin near the rostrum a little hollowed
out; tergo-lateral slip, apparently formed by upturned lines of
growth,
broad, rounded, and protuberant. Terga broad, almost square. Carina,
with the basal margin apparently pointed.

Oxford Clay, Middle Oolite, attached
to an Ammonite.
Mus.
Pearce.

Although
to my great regret the state of Mr. Pearce's health has prevented him
allowing me to examine the specimens in his possession, yet I have
thought it advisable to commence the genus with this species, as it is
in a far better state of preservation than any other specimen hitherto
discovered. We gain by a single glance the knowledge that at so remote
a period as the Middle oolite a true Pollicipes existed. In no other
instance that I have heard of, has the peduncle been perfectly
preserved. Mr. Morris first named and briefly described this
interesting species; subsequently Mr. James Sowerby has given enlarged
drawings (without any description) of it in the 'Mineral Conchology;'
and it is from these figures that I have drawn up my specific
description, which, from this cause, is necessarily imperfect. The
figures in this volume are copied from those in the 'Mineral
Conchology,' which I may remark have evidently been executed with great
care, and Mr. Sowerby's accuracy of observation is universally well
known. The peduncle is several times longer than the capitulum: Mr.
Morris describes the scales on the peduncle as being small, closely
pressed together, somewhat quadrate in form, and each regularly marked
by a transverse carinated ridge; this latter character I do not
understand. The rostrum is not clearly figured by Mr. Sowerby, but I
believe that I can see evidence of its existence. From these materials
it would appear that the P. concinnus is more nearly related
to the recent P. cornucopia, and its two nearest congeners,
than to any other species of the genus.

Scuta
triangular; surface undulatory; basal margin at right angles to the
straight tergo-lateral margin; there is no tergo-lateral segment
formed
by upturned lines of growth. Carina nearly straight,
semicylindrical, with the basal margin square.

My
materials consist of several scuta, terga, and carinæ, kindly lent me
by Professor Buckman, and of another set (which includes the rostrum)
presented by him to the Geological Society of London.

Valves:
these have a smooth surface, but are undulatory in the direction of the
lines of growth; at the cessation, apparently, of each zone of growth,
there was a tendency to form a projecting ridge or plait, as takes
place in a far more marked manner in some of the cretaceous species,
namely, P. elegans and fallax. There are also
excessively fine, longitudinal striæ, which can be seen only when the
valves are held in particular lights; these seem to have been formed
by
the so-called epidermis, which we know in the recent P. mitella
is longitudinally and finely ribbed. Scuta (fig. 2, c)
but slightly convex; triangular; basal margin straight, forming a
right
angle with the tergo-lateral margin, and rather less than a right angle
with the slightly arched occludent margin; the tergo-lateral margin is
straight, and not at all protuberant: in the figure the left hand is,
as usual, the occludent margin; I mention this because the valve has a
reversed appearance, owing to the unusually small angle which the
occludent makes with the basal margin. Terga (fig. 2, d)
rhomboidal, slightly convex, with a rounded ridge, which is central,
running from the apex to the broad, rounded basal angle; the upper
carinal and occludent margins stand at right angles to each other, and
are short compared to the scutal and lower carinal margins; there is
no
trace of a depression parallel to the occludent margin. Carina
(fig. 2, a, b) elongated, triangular; scarcely at
all bowed
inwards; not even sub-carinated; basal margin rounded, not
at
all protuberant. The Rostrum differs from the carina only in
its greater breadth compared to its length.

Dimensions.
The largest scutum is .6 long, but as there is a broken tergum about
1.1 long, no doubt the species attained a rather large size; the
longest carina is .7 in length.

Diagnostic characters.
This species is best characterised by the straightness of the whole
tergo-lateral and of the basal margin of the scuta; by the ridge being
central on the terga; by the carina not being carinated; and by the
sinuous state of the surface of the valves, intermediate between the
smooth species and those with distinct ridges parallel to the zones

of growth. The remarkable straightness of the tergo-lateral margin
of the scuta is like that in the recent P. spinosus and serta,
and in Scalpellum villosum,
in all which species, I may observe, the scuta and terga are separated
by an interspace of membrane; in these three recent species, however,
the basal margin is considerably protuberant. The present species
differs apparently from the P. concinnus of the Oxford clay,
in the basal and tergo-lateral margins of its scuta being straight; in
the greater proportional length of the scutal and1

Scuta
triangular, flat; basal margin forming nearly a rectangle with the
occludent margin, and a somewhat lesser angle with the straight
tergo-lateral margin. There is no tergo-lateral slip formed by upturned
lines of growth. Carina much bowed inwards, massive, with the basal
margin bluntly pointed.

Scania (Balsberg, Kopinge, Ffo.,
&c.) Mus.
Univers. Copenhagen.

Professor
Steenstrup has described, under the name of Pollicipes Nilssonii,
a
large carina, and apparently a sub-carina and rostrum, and he remarks
that these perhaps belong to the same species with the terga, named by
him P. undulatus. M. Angelin, however, believes that the
latter belong
to the species already described as Scalpellum solidulum.
With the
specimens of the present species, M. Angelin has lately found three
small scuta, which he believes belonged to it. These scuta are so
extremely worn, that I should not have ventured to have named them, had
it not been advisable to give figures of the remarkable carina already
named as P. Nilssonii. Should it hereafter be proved that the
following
scuta belong to some other carina, then a new name will have to be
attached to them.

Scuta (fig. 11, a) flat,
thick, triangular, not much acuminated; basal margin forming almost a
rectangle with the occludent margin; tergo-lateral margin (in present
condition) straight, forming a rather less angle with the basal than
does the occludent margin. There is no trace of a slip or portion of
valve along the tergo-lateral side, formed by upturned lines of growth.
Internally, the pit for the adductor muscle is deep; the central
portion of the apex above the pit is prominent; apparently there was
no
internal furrow. Length of longest specimen only .4 of an inch.

Carina
(fig. 11, b, c) strong, with the upper part
unusually massive; though
in a worn condition, there are distinct traces of its having been
longitudinally and slightly ribbed. Strongly carinated, the two arched
sides meeting each other at about a rectangle; much bowed inwards, and
widening much from the apex to the base; upper portion, about one
fifth
of the entire length of the carina, seems (for the worn condition
prevents certainty) to have projected freely; beneath the upper freely
projecting portion, the inner margins are nearly straight; the depth
of
the shell, measured from the central crest to the inner margin, is, in
the lower half, remarkably great, and consequently the valve in the
same part is internally concave to a remarkable depth; the upper
freely
projecting portion is only slightly concave, and is singularly massive,
from having been filled up with solid shelly layers. The basal margin
is bluntly pointed, the edges meeting each other at about a right
angle; in the lower part of the valve the lines of growth are of
course
parallel to the basal edges, but higher up they meet at a more open
angle, and consequently the carina of a young individual must have had
its basal margin less projecting. When the sides of the carina are
examined carefully, a portion, about one fourth of its entire depth,
can be observed to lie a very little more inwardly inflected than the
more central part, so as not to form quite a continuous surface with

lower
carinal margins compared with the upper carinal and occludent margins
of the terga, and lastly in the basal margin of the carina being
truncated; it differs from P. planulatus of the Oxford Clay,
and therefore its other nearest relative in age, by the basal angle of
the terga being rounded, instead of square as in that species.

the
two broad arched roof-sides; and in these slips the lines of growth
run
almost parallel to the inner margin of the valve: in this respect the
valve approaches in character to that of Scalpellum. The
heels or
baso-lateral angles apparently projected slightly, as I infer from a
slight downward curvature in the lines of growth, along a line
corresponding with the heel, and separating the roof-part from the
inflected walls of the carina.

Sub-carina
(fig. 11, d): in Professor Steenstrup's collection there are
several
worn valves which appear to have been sub-carinæ; in shape
approximately semi-conical; the basal margin being almost semi-oval,
with the two corners a little inflected; hence the valve is deeply
concave to an unprecedented degree, and this is quite conformable with
the singular sectional outline of the carina (c). About one
fourth part
of the length of the valve must have projected freely; the outer
surface is longitudinally ribbed, and the lines of growth remarkably
undulatory.

Rostrum (fig. 11, e): this valve
which I believe to be the rostrum resembles the sub-carina, but is more
open, less high, and with a larger proportion, namely half, of its
entire height freely projecting; the semi-oval basal margin is
slightly
sinuous, the projecting points corresponding with the external
longitudinal ribs.

Length of carina, 1.5; of the largest of the
sub-carinæ, .6; of the largest rostrum, .45 of an inch.

Scuta, subtriangular, with the
baso-lateral corner much rounded, and with the apex produced; basal
margin forming nearly a right angle with the occludent margin; apex
with its internal surface prominent, and with the tergal edge furrowed.

Hilsthon, des Elligser Brinkes. (Lower
Greensand, Germany.)

Messrs.
Koch and Dunker have given a full and detailed account of this species,
together with truly excellent figures, and I have nothing to add to
their remarks, but will re-describe, for the sake of uniformity, the
valves of this species, which, through the kindness of Professor
Steenstrup and Professor Dunker, I have examined. The valves are
slightly worn. The figures given in tab. III are not, I think, so good
as most of the others.

Scuta (Tab.
III, fig. 3, b, c) moderately convex,
sub-triangular; apex much
acuminated, slightly curved towards the terga; surface smooth, faintly
marked with zones of growth, and, especially near the apex, with faint
lines and furrows radiating from it. There is no distinct ridge
proceeding from the apex to the baso-lateral angle, which is so much
rounded that the basal margin blends into the tergo-lateral; it must,
however, be remarked, that the specimens are worn. The occludent margin
stands at right angles to the basal; and the lower part of the
tergo-lateral margin forms rather above a right angle with it.
Internally (c), there is a deep pit for the adductor scutorum,
and in
the upper part, close to the tergal margin, a deep furrow; the central
portion is prominent; the occludent margin keeps nearly of the same
thickness up to the apex of the valve.

Scuta,
almost rhomboidal, excessively smooth, basal margin forming above a
right angle with the occludent margin, which latter is exteriorly
furnished with a linear, minute, wall-sided ledge; apex with its
internal surface concave.

Mus. Bowerbank. Locality
and formation unknown; from the state of another specimen fastened on
the same board, I think probably from the Gault; the colour of the
substance in the cracks of the valve countenances this same opinion.

I
have been unwilling to fix a specific name to a single, much broken
scutum; but as even in its present state it can be clearly seen to be
distinct, and as this is the typical valve in this genus, I have felt
myself compelled to do so.

Scutum sub-rhomboidal,
approaching to oval in outline: rather thin; surface excessively
smooth; slightly convex, but with a narrow portion along the occludent
margin, somewhat inflected: exteriorly close to this same margin, or
rather almost forming it, (b) there is an extremely narrow,
sharp, wall-sided, projecting ledge. The occludent margin is slightly
arched, and forms, with the basal margin, an angle considerably above a
right angle, so that the whole baso-lateral corner of the valve is much
produced: the lower part of the tergo-lateral margin is at right
angles
to the basal margin. Baso-lateral angle smoothly rounded, with no trace
of a ridge running from it to the apex, though this is the line of
chief flexure of the valve. Internally, the valve has been much
injured; the de-

protuberant; surface smooth,
but near the pointed, slightly curled apex, it is marked by fine
radiating lines; carinal margin regularly curved from the apex to the
basal angle, which latter is not very sharp. A curved ridge (formed by
the surface of the shell being lower on the carinal than on the other
side) connects the upper and basal apices, running almost parallel to
the carinal margin, and at about one-fourth of the entire width of the
valve from the latter margin. Occludent margin shorter than the scutal; rounded, protuberant, with a depression parallel to it; the scutal
margin, corresponding with this depression, being slightly hollowed
out; a small portion of the apex projects freely. Internally, and
nearer to the occludent than to the carinal margin, there are three or
four short parallel longitudinal ridges or crests, as described in
Scalpellum arcuatum.

Carina (Tab.
III, fig. 3, a) moderately bowed inwards, widening gradually
from the
apex to the basal margin, which is rounded and protuberant, and with a
trace of an angular bend in the middle; exteriorly the surface
presents
just a trace of being sub-carinated; roof convex; the upper part of
the
valve projects freely.

Rostrum: Koch and Dunker figure valves,
which, from their general appearance,
breadth, and apparently large proportional upper, freely-projecting
portion, I have little doubt have been rightly considered by them as
rostra; they are, however, longitudinally plicated or striated to a
greater extent than the other valves.

pression
for the adductor scutorum does not appear to have been deep: the
concavity of the valve extended to the apex, with the upper part not
filled up solid; a considerable portion of the upper tergal margin is
marked by lines of growth, and must have overlapped the tergum, but
there is no trace in it of a recipient furrow.

Affinities.
This species seems quite distinct from all others; and I can hardly
say
to which species it is most related; in some few respects it comes
nearest to P. acuminatus.1

Scuta
almost square; occludent margin and the lower part of the
tergo-lateral
margin at right angles to the basal margin; apex blunt.

White Chalk, Denmark. Mus.
Univers.
Copenhagen.

General Remarks. Professor Steenstrup at
first described this species as distinct, but subsequently considered
it the same with P. lævis
of Sowerby; this is not the case, and therefore I have retained the
name first given, though very inappropriate to the more important
valve. According to the practice here followed, the species is founded
on the scutum, of which a mere fragment and impression exists, but it
is sufficient to show that it is distinct. In the same chalk with this
scutum, there are two terga which are different from any other seen by
me, and which Professor Steenstrup has described as belonging to this
species, a view which I have followed with some hesitation.

Scutum
(fig. 5, c, b) nearly smooth, but with the
growth-lines
plain; thin, very
slightly convex; oblong, almost rectangular, but with the upper
lateral
corner rounded off. Occludent and lower part of tergo-lateral margin
both straight, and at right angles to the straight basal margin: upper
part of tergo-lateral margin much arched and protuberant, which,
together with the blunt apex given to the valve, it is almost
rectangular, oblong outline. A trace of a ridge runs from the
baso-lateral angle to the blunt apex. The figure given is a
restoration; being guided by the outline impressed on the chalk, and
the lines of growth as seen on the small baso-lateral preserved portion.

Tergum
(fig. 5, a), convex, thick, elongated, sub-rhomboidal, or
rather
triangular, for the upper and lower carinal margins blend into each
other with quite a uniform and gentle sweep: upper part of the carinal
and occludent margins meet at an angle of about 45°; from the apex to
the sharp basal angle, an angular, very slightly curved, conspicuous
ridge runs at about one third of the entire width of valve from the
carinal margin: the surface of the valve slopes rather steeply away on
both sides from this ridge. Occludent and scutal margins about equal in
length; parallel to the former, a rather wide space of the valve is
slightly depressed, with a corresponding portion of the scutal margin
slightly indented; the occludent margin itself is not rounded and
protuberant, as if it had been received in a furrow in the scuta. A
considerable portion of the upper part of the valve projected freely.
This valve more resembles the homologous one in the Italian tertiary, P.
carinatus,
than that of any other species: as before stated, I assign it to this
species on the excellent authority of Professor Steenstrup; I may,
however, remark, that it appears much thicker and stronger than the
scutum. The figure of the tergum (a) is not very good, and has been
drawn on too small a scale.

Scuta
elongated, triangular; basal margin forming much less than a right
angle with the occludent margin; apex, with its internal surface
concave.

White Chalk. Mus. Flower,
(believed to
have
come from the Lower Chalk of Stoke Ferry, Norfolk).

My
materials consist only of a single left-hand scutum, and that with the
whole of the basal margin broken off; nevertheless, there can be no
question that it is quite distinct from all the species hitherto
described.

Scutum: shell rather thin, surface
extremely smooth; triangular, much elongated, with the upper part a
little bent over towards the terga: slightly convex, but with the
whole
middle part of the valve remarkably flat; the convexity being caused
by
the inflection, in a slight degree, of the occludent margin, but
chiefly of the tergo-lateral portion; hence, a smooth ridge of chief
curvature runs from the apex to the baso-lateral angle. Occludent
margin arched, forming less than a rectangle with the straight basal
margin, with which the very slightly concave tergo-lateral margin forms
an angle rather above a right angle: the tergo-lateral portion of the
valve, formed by the upturned zones of growth, moderately wide, being
in the upper part about one third of the entire width of the valve:
rostral angle rounded. Internally (b) the valve is singular;
the depression for the adductor scutorum muscle is extremely faint, and
is situated unusually low down in the valve, though the exact relative
position must at present remain unknown, as the basal margin has been
broken off. But the most unusual character, at least in the cretaceous
species of Pollicipes, is, that the concavity of the valve runs up to
the apex, and must have been lined up to that point with corium; the
flat internal occludent edge, marked by lines of growth, widens very
little in the uppermost part.

in
Mr. Fitch's Collection: also a single scutum sent me by Professor
Steenstrup, and found by M. Angelin, after whose name I have called
this well-marked and peculiar species.

Scuta (fig. 7, a, b);
triangular, much elongated, considerably convex, apex extremely
acuminated; basal margin at nearly right angles to the straight
occludent margin, but near to the rostral angle, it is produced in a
remarkable manner into a rounded, obliquely truncated broad point.1
The tergo-lateral portion of the valve, formed by the upturned lines of
growth, is not much developed: the tergo-lateral margin, as seen
externally, is obscurely divided into two lines, of which the upper, or
tergal portion, has its edge reflexed; this same whole margin,
however,
seen internally, appears nearly straight, and this is essentially the
case; the projecting angle being connected with the thickening of the
valve during growth. The exterior surface is smooth, with some faint
longitudinal striæ: a single ridge, or rather, line of flexure, runs
from the apex to the baso-lateral angle. Seen internally, the uppermost
part of the valve is found to be unusually thick and solid, with the
pit for the adductor scutorum muscle well developed, and placed rather
low down. The internal occludent edge (b), marked with lines
of growth, becomes close above the adductor depression suddenly very
wide, and forms a deep furrow, which I at first thought was formed to
receive the occludent angle of the terga; but upon consideration, I
feel pretty sure that this cannot have been the case, and I believe the
furrow to be of no functional importance, but to result from the sharp
apex of the still corium-covered portion of the valve having been
greatly thickened: this same upper portion has, in most specimens, in
its middle, a slight linear furrow. On the tergal margin of the
internal surface there is a small portion, marked with lines of growth,
which is obliquely truncated, owing to the valve having become very
thick; and this must have overlapped the tergum. From these
peculiarities in the internal surface of the apex of the scuta, it may
be inferred, that the terga, owing to the probable close contact of the
two valves, would present peculiarities of a corresponding nature. The
largest British specimen is .8; and the Scanian specimen is .95 of an
inch, in length.

Terga (fig. 7, c, d); in
Mr. Fitch's collection there are, from the same formation in which the
above scuta were found, two terga, remarkable from a very wide
square-edged depression, running parallel to the occludent margin,
which is itself rounded and protuberant: these valves probably
belonged
to the P. Angelini, and anyhow may be conveniently here
described. Valve
rhomboidal, not very flat, smooth, with a conspicuous ridge, wall-sided
on its carinal aspect, running almost down the middle of the valve from
the apex to the basal angle, which latter is not very sharp. The upper
carinal and occludent margins meet each other at slightly less than a
right angle; occludent margin a little longer than the scutal margin,
with its edge thickened, rounded, and protuberant to an unusual degree; alongside the occludent margin an unusually broad and deep,
square-sided depression runs, equalling in width about one third of the
scutal margin; a

1 Amongst the
Scanian fossils from Kopinge, there is a scutum with the whole upper
part broken off, but which I think belonged to this species; if so, it
differs from all the others in the rostral portion of the basal margin
projecting very little.

transverse section across the middle of the valve is given in fig.
7, d, exhibiting its peculiar outline.

Carina.
In Mr. Fitch's collection there are two carinæ which probably belonged
to this species, at least they do not belong to the only two other
species of Pollicipes, (viz. P. fallax and striatus,)
found by this gentleman in the chalk near Norwich. These carinæ are
identical, as I know from examination, with that (also from
Norwich) figured by Mr. Sowerby, (Min. Conch., Pl. 606, fig. 7,) as the
anterior valve of his Pollicipes sulcatus, Scalpellum
maximum,
var. sulcatum
of this work. These two carinæ differ a little from each other in the
basal margin, being either rectangularly pointed or rather blunter and
more arched; their surfaces are smooth, but in one specimen there are
some obscure longitudinal striæ; in outline they are tapering,
triangular, almost straight, transversely flatly arched, subcarinated,
edge inflected, with the lines of growth bowed downwards, and
consequently with the basal lateral angles or heels a little prominent.
Finally, these carinæ cannot be strictly distinguished from the same
valve in P. glaber and unguis, but as I believe
neither of these species occur in the upper chalk near Norwich, they
can hardly belong to them.

Affinities.
The scuta in this species differ from all others in the projection of
the basal margin, close to the rostral angle; a somewhat similar
projection, I may remark, sometimes occurs in the scuta of the recent Lepas
fascicularis, A. vitrea of Lamarck. Internally, the
valve more
resembles that of the second and third varieties of Scalpellum
maximum than any other species. The terga can be distinguished
from those of P. glaber only by the depression along the
occludent margin being deeper, wider, and square-sided.

Scuta; thin, suboval, with the
basal margin forming an angle much larger than a rectangle with the
occludent margin; a faint rounded ridge runs from the apex to the
baso-lateral angle, dividing the valve into two nearly equal halves. Carina
linear, in a transverse line steeply arched; basal margin much
produced, with its apex truncated. Upper Latera subpentagonal.

mens,
consisting of a scutum, terga, carinæ, and upper latera; and to Mr. F.
E. Edwards the loan of several very perfect specimens.

Valves; smooth, rather thin. Scutum (fig. 8, e)
elongated, very slightly convex, many-sided, almost oval, with its
upper point produced, but apparently apt to be broken off. Occludent
margin slightly arched; basal margin consists of two sides, of which
the rostral side is extremely oblique to the other, the two sides
together forming a very large angle with the occludent margin; the
tergo-lateral margin also consists of two sides, meeting each other at
a very open angle; the lower half forms above a rectangle with the
basal margin; possibly this lower half corresponds with the
widely-truncated baso-lateral angle in P. dorsatus, and with
the smaller similar angle in the tertiary P. carinatus.
A faint rounded ridge runs from the apex to the baso-lateral angle, and
thus divides the valve into two nearly equal halves. Internally there
is a deep pit for the adductor muscle; only a narrow internal edge
along both sides of the apex is marked by lines of growth.

Terga (fig. 8, d);
elongated, rhomboidal, flat and thin; carinal margin continuously
curved; apex much produced; the occludent and upper carinal margins
meet each other at much less than a right angle; occludent margin
slightly longer than the scutal margin, which latter in the upper part
is very slightly hollowed out; a faint, rather wide ridge, runs down
the centre of the valve to the rectangularly-pointed basal angle; a
small portion of the upper part of the terga projected freely.

Carina fig. 8, a, b, c);
narrow, with the lower part somewhat spear-shaped; almost straight,
transversely convex, with the central part forming a broad rounded
crest; lateral margin a little inflected; basal margin
extraordinarily
produced, with its apex square; internally, the corium-covered surface
is produced upwards into the sharpest apex; a small portion only of
the uppermost part of the valve projected freely.

Upper Latera (fig. 8, f);
flat, almost pentagonal, with the two upper margins considerably longer
than the three lower ones; of these three, the carinal margin is the
shortest, and the other two equal, with the rostral one considerably
arched or convex; these three basal margins must have been in contact
with the Latera of the lower whorl; the apex did not project freely. I
have not seen any latera of the lower whorl, but Mr. Sowerby gives
figures of some minute valves, which no doubt were such. Several of Mr.
Edwards's specimens are tinged a pale-reddish purple.

Dimensions. The valves described are all rather small; the
largest, a tergum, is a little more than a quarter of an inch in length.

Affinities. This species is more nearly related to the
section of the genus containing the recent P. cornucopia, elegans,
and polymerus, than to the other sections. Its affinity is
closest to P. cornucopia, though in the form of the basal
margin of the scuta there is more resemblance to P. polymerus.
The scutum presents some points of resemblance to the cretaceous P.
gracilis and dorsatus.

Scuta
moderately thick, in shape nearly an equilateral triangle; occludent
margin exteriorly strengthened by a slight ridge; a strong ridge runs
from the apex to the middle of the basal margin; basal margin straight; baso-lateral angle truncated, short: the tergo-lateral portion, formed
by upturned lines of growth, is absent. Carina, exteriorly,
strongly
carinated, with a lateral furrow on each side.

Tertiary; Messina, Sicily.

I
owe to the great kindness of Dr. Phillippi an examination of an
authentic series of specimens. Valves rather thick, with the lines of
growth plain, and with a few fine striæ radiating from their apices:
these striæ are sometimes so conspicuous, that I have doubted whether
the species ought not to have been placed in the next section.

Scuta
(fig. 9, d, e); triangular, with the apex slightly
bowed over towards
the terga; moderately convex; occludent margin slightly arched, about
equal in length to the slightly hollowed-out tergo-lateral margin;
basal margin nearly straight, though formed by two lines meeting each
other, sometimes with the rostral half not descending so low as the
other half; this margin forms equal angles with the other two margins.
The baso-lateral angle is obliquely truncated: there is no
tergo-lateral slip formed by upturned zones of growth. The occludent
margin is exteriorly strengthened in a manner only just perceptible by
a flattened rim. A strong, conspicuous, and prominent ridge runs, in a
slightly curved course, from the apex to a point in the basal margin,
rather nearer to the rostral than to the baso-lateral angle; this
point
just perceptibly projects beyond the rest of the basal margin: the
ridge is either moderately sharp, or broad and flat-topped; it marks
the line of chief curvature of the valve. Internally (e), the
pit for
the adductor muscle is not very strongly developed, and to a different
degree in different specimens: the internal surface of the centre of
the apex is prominent; on its tergal side there is no furrow, but a
rectangular indentation formed by a remarkably wide, flat, smooth
ledge, which runs down, narrowing, to the baso-lateral angle; hence
the
scuta along the whole of this side, especially in the upper part, must
have widely overlapped the terga, in a manner and to a degree I have
not seen equalled in any other Pollicipes; but the two valves cannot
be
said to have been articulated together. The internal occludent edge
widens a little in the upper part, and is here divided by an oblique
line, with the lines of growth apparently discontinuous on opposite
sides of it, into two portions, of which the inner portion is slightly
more prominent than the outer. I have already alluded to the fact, that
in some specimens the scuta are strongly ribbed longitudinally, in some
very faintly striated, and in others smooth.

Terga
(fig. 9, a, b); sub-rhomboidal, elongated,
exteriorly convex,
internally very slightly concave: upper part very thick and solid,
with
a considerable portion freely projecting, and internally marked by
lines of growth: along the middle of the portion thus marked, there is
a slight longitudinal depression, which is worth remarking, inasmuch as
(judging from a conspicuous and analogous character in certain recent
species of Lithotrya) it was probably caused by the internal central
crest of the upper part of the carina. Occludent margin slightly
convex, very little shorter than the scutal margin; upper and lower
carinal margins nearly equal in length; they meet each other at a very
open angle: upper carinal and occludent margins meet each other at an
angle of only a little above 50°. A prominent, strongly marked ridge,
(with both sides of the

valve
sloping from it,) runs from the apex to the sharp basal angle: this
ridge is very slightly curved in two directions, like the letter S, it
runs at about one third of the entire width of the valve from the
carinal margin.

Carina (fig. 9, e, f)
strong and solid, with lines of growth
conspicuous on its
surface; very slightly arched inwards; triangular, moderately
tapering;
transversely moderately convex, very plainly carinated, with a slightly
projecting rib; on each side, at a little distance from the lateral
edges, there is a distinct and linear furrow, and these edges
themselves are, partly in consequence, rounded and slightly
protuberant: basal margin square, and not at all protuberant.
Internally, the upper part, for about one third of the total length of
the valve, must have projected freely, and has been filled up solid
with a trace (f) of a central crest: the internal lateral
edges are
slightly scalloped out along the whole length of the valve.

Rostrum
(fig. g, h, i); broad, triangular:
apex curled inwards to a most
remarkable extent, so as even to point a little downwards; basal
margin
just perceptibly protuberant, with a square projection formed by the
end of a wall-sided, broad, flat-topped ridge, running down from the
apex; Phillippi, however, states, that the form of the basal margin
varies. Internally, a full upper half of the valve projected freely;
the internal upper surface is smooth and concave, with just a trace of
a fine central crest: the inwardly curled apex converts the upper part
into a hood: the central basal projection is channelled, the channel
running a little way up the valve, and being gradually lost: this
channel, no doubt, allowed a filament of the corium to pass to the
sub-rostrum.

Peduncle. Dr.
Phillippi has sent for my inspection, a rare and interesting specimen
of a peduncle, with the scales preserved, no doubt, belonging to this
species. The scales, as usual, decrease downwards in size; they are
rather broad; each has its upper end rounded; is marked transversely
by
lines of growth, and has a slight external, central, longitudinal
crest: this crest is wedge-formed, being widest at the apex. I have
not
seen this latter character in the peduncular scales of any other
Pollicipes; there are, however, traces of it in the small lower Latera
in P. mitella; it is apparently caused by the lateral
overlapping of the closely-packed scales, and chiefly when the specimen
was young.

Affinities.
The general form of the carina, with its lateral furrows and rounded
protuberant margins,—its carinated central line;—the shortness, and
great inward curvature of the rostrum, with its strong, central ridge,
terminating in a channelled projection on its basal margin—show a clear
affinity between this species and the recent P. mitella of
the Eastern tropical seas. There are some points of resemblance in the
scuta and terga to the same recent species; but in the scuta a closer
affinity is shown to P. dorsatus; and in the terga to those
described under P. elongatus: in the manner, moreover, in
which the upper part of the carina is
filled up and furnished with a central crest, there is a relationship
to P. validus. The affinity of P. carinatus to P.
mitella is interesting; because we may with some confidence infer
from the relationship between P. carinatus, dorsatus,
validus, and rigidus, that, in these several
species, the
valves, which hitherto have been found only separated, were united
together to form the capitulum in a somewhat similar manner as in the
well-known recent P. mitella.

Scuta moderately thin, rather broad, approaching to an
equilateral triangle; basal margin not quite straight; the
tergo-lateral portion, formed by the upturned zones of growth, where
widest, half as wide as the rest of valve; apex internally
furrowed
on the tergal side. Carina with the basal margin bluntly
pointed. Upper latera triangular, one third the length of the
terga. Anterior lower latera, each with a ridge running to
near one end of their basal margins.

General remarks.
My materials consist of several scuta, in Mr. Flower's collection from
Stoke Ferry, together with some carinæ, and a rostrum of apparently the
same species; of a single scutum from Northfleet, and of others from
Charing, both in Kent; of some scuta, terga, and carinæ, sent me by
the
great kindness of Roemer, from Sarstedt, near Hildesheim, and therefore
authentic specimens by him named; and lastly, of a valuable specimen
from Gravesend, in Kent, in Mr. Bowerbank's collection (fig. 10, a),
in which a carina, pair of terga, an upper latus, and two lower latera,
were embedded in nearly their proper positions, together with a
fragment of a scutum, which latter is sufficiently perfect to leave no
doubt on my mind regarding its identity with the valves from Stoke
Ferry, Northfleet, and Sarstedt. This appears to have been one of the
commonest species of Pollicipes during the cretaceous period. Though
found in the upper chalk of Northfleet and Gravesend, it is singular
that not a single valve of this species has been collected by Mr. Fitch
in the upper chalk of Norwich. Amongst the Scanian fossils, collected
by M. Angelin at Kopinge, from a still higher stage of the chalk, and
forwarded to me by Professor Steenstrup, there is an upper latus and
tergum most closely allied, probably even identical with the present
species. We have seen that it extends down even to the pläner or chalk
marl.

Scuta (fig. 10, b, c, d). These
valves are moderately thick and convex, so that in their upper halves
they are almost semi-conical; the basal margin is not quite straight,
it forms a rather larger angle with the lower part of the tergo-lateral
margin, than with the occludent margin, both angles being less than
right angles. From the apex two faint ridges run, one to the
baso-lateral angle, and the second to a point in the basal margin, a
little nearer to the rostral than to the baso-lateral angle. The valve
is bent, so as to be convex, chiefly along these two ridges. The
tergo-lateral portion formed by the upturned lines of growth is wide
and protuberant. Outer surface of valve smooth, with the faintest
striæ radiating from the apex. Viewed internally (d), a
conspicuous furrow runs from the pit for the adductor scutorum muscle
up to the apex; the internal occludent edge keeps the same width up to
the apex. The Sarstedt specimen is the largest scutum which I have
seen, and that is .6 of an inch in length.

One out of Mr.
Flower's five specimens (believed all to have come from the lower chalk
of Stoke Ferry) and another in Mr. Wetherell's collection from the
upper chalk of

Northfleet, present some slight differences, in the valve being
flatter, in the tergo-lateral portion being more developed, and in the
basal margin being straighter; but these differences are so very
slight
that it would be exceedingly rash to consider them as specific.

Terga (fig. 10, e, a);
rhomboidal, flat, with a straight slight ridge running, at about one
third of the entire width of the valve from the carinal angle, to the
sharp basal angle; this ridge is steep on its carinal side, on which
side the whole surface of the valve is somewhat depressed. The upper
carinal margin meets the occludent margin at somewhat less than a right
angle: the occludent margin slightly exceeds in length the scutal
margin; the valve is widest nearly in its middle. A narrow rim along
the occludent margin is slightly protuberant, within which there is a
slight parallel depression. The scutal margin is not quite straight;
the lower half (which probably was in contact with the upper latus)
projecting a little.

Carina (fig. 10, f, g);
triangular, tapering, moderately strong, with a smooth surface; almost
straight or slightly curved inwards; transversely, flatly arched,
sub-carinated. Lateral margins narrow, inflected, with the lines of
growth first curved downwards (g), and then on the edge itself
abruptly upturned; basal margin bluntly pointed, apparently in a
variable degree. The two baso-lateral angles are slightly prominent, in
conformity with the above-stated direction of the lines of growth along
the margin. I may remind the reader that this valve, the terga, and the
latera presently to be described, were all embedded together in their
proper positions.

Rostrum (fig. 10, h, i):
in Mr. Flower's collection, with the other loose valves from Stoke
Ferry, there is one which I can hardly doubt is a rostrum: it is
nearly
an equilateral triangle; externally convex, sub-carinated, basal
margin
not protuberant. The upper part, for about one fourth of the entire
length of the valve, must have projected freely; this part is
remarkable, from having been filled up internally with a central crest,
like the carina of P. validus and carinatus.

Upper latus (fig. 10, k, a);
flat, almost an equilateral triangle, but with the two upper sides not
exactly equal, and both a very little longer than the basal margin;
umbo of growth at the uppermost point; length, one third of the terga; surface smooth, with no trace of a central longitudinal ridge;
internally the edges are bevelled, and a very small portion of the apex
must have projected freely.

Lower latera (fig. 10, l, a). There are
two of
these (one much broken) nearly resembling each other: from analogy
with
the latera of P. unguis,
these are probably from the rostral end of the capitulum; they are
slightly convex, and approximately form a transversely elongated
triangle, with one corner cut off; the two upper sides are slightly
unequal in length: umbo of growth at the apex, from this point a
narrow
well-defined ridge runs obliquely across the valve, to the most
protuberant point of the basal margin, which is situated about one
fourth of the entire width of valve from one end. These lower latera
are wider than, but not so high as the upper latus: seen internally
the
edges are bevelled, and a very small portion of the apex must have
projected freely.

As it is so very rare to find the valves of a Pollicipes united, it
will be advisable to give

the
measurements of the Gravesend specimen: the scutum is too much broken
to be measured, and the breadth only of the basal margin of the carina
can be given—it is .25 of an inch; the terga are nearly .8 long and
fully .4 broad. The upper latus is .27 in height, basal margin .23 in
length. Lower latus .2 in height and .26 in breadth. I imagine that the
broken scutum belonging to this individual, was fully two thirds of the
size of the largest scutum which I have seen, namely, that from
Sarstedt, .6 of an inch in length.

Affinities. From the very close affinity of this species to
the following one, P. unguis
of the Gault, we may safely infer that it had not only a rostrum (of
which a specimen found separately has been described), but also a
sub-rostrum; whether it had a sub-carina, as is probable, must remain
doubtful. The two faint ridges running from the umbo of each scutum to
its basal margin, probably mark the extent to which this valve was
overlapped, as in the case of the recent P. mitella, by the
rostrum and upper latera; and the ridge on the terga, steep towards
the
carina, probably shows the extent to which this latter valve reached.
It is also probable, as we shall see under the head of P. unguis,
that there was only one whorl of valves under the upper latera, and
that this included the sub-rostrum: the latera in this lower whorl
were
probably not very numerous, but large, and of very unequal sizes;
their
mutual overlapping no doubt caused the oblique ridges on their exterior
surfaces.

General Remarks. This species comes very close to P.
glaber,
but can, I think, be safely distinguished from it, even with our
present materials. A specimen most unusually perfect is in the Museum
of Practical Geology; it consists of a carina and pair of terga,
much
mutilated, a rostrum, sub-rostrum, a pair of upper latera, a pair of
latera of the lower whorl from the carinal end of the capitulum, and
two other latera of this same

whorl
from one side of the rostral end of the capitulum. All these valves are
magnified twice in fig. 1, Tab. IV; and as all, except (d),
belonged to the same individual, we here have the rare advantage of
learning their relative sizes. The largest of the lower latera has been
mistaken for a scutum, and has been thus figured by Mr. Sowerby; the
mistake was a very natural one, to be rectified only by examining the
under side of the specimen. Although the scutum is, unfortunately, at
present unknown, there can be scarcely any doubt that it would closely
resemble that of P. glaber, and therefore I have not
hesitated, in this instance, to break through my rule of exclusively
taking the scutum as typical in Pollicipes: should,
hereafter, a scutum be found in the Gault like that of P. glaber,
it may, with considerable confidence, be named as belonging to this
species.

I have felt considerable doubts regarding the nomenclature of this
species: P. unguis
is founded on one of the latera of the lower whorl, and on what
apparently is a rostrum; these valves are at present, and will
probably
for very long remain insufficient for the foundation of a species. P.
lævis
is founded on a tergum and carina, and therefore on better grounds. The
specimen immediately to be described, leads me to believe that all
these valves belong to the same species; and therefore both names were
open to me. Mr. Sowerby, however, has given in the same volume of the '
Geological Transactions,' the name of P. lævis to a carina
and tergum from Blackdown, which, I cannot doubt, is distinct:
Professor Steenstrup has also described a new form under the same name
of lævis; such being the case, it has appeared to me
advisable to take the name of P. unguis.
I must add, that there is some considerable variation in the terga from
the Gault, which renders it just possible, but not probable, that there
may be a second closely allied form. It is very singular, considering
how very frequent terga are in all collections, that I should not have
seen a single scutum which could, as I believe, have belonged to this
form.

Scutum unknown. Tergum (Tab. IV, fig. 1, b,
c); this is a medium-sized specimen, .5 or .6 of an inch in length; it is
rhomboidal, nearly flat, with a straight, slight ridge, running from
the apex, at about one third of the entire width of the valve from the
carinal angle, to the sharp basal angle: the ridge is steep on its
carinal side, on which side the whole surface of the valve is somewhat
depressed. The upper carinal margin meets the occludent margin at
somewhat less than a right angle. Internally, a rather small portion of
the apex is marked by lines of growth; and close along the upper
carinal margin there is a narrow furrow (b), with a ridge
parallel and exterior to it; both furrow and ridge are rather
variable,
and, no doubt, are produced by contact with the edge of the carina. The
occludent margin very slightly exceeds in length the scutal margin;
the valve is widest nearly across the middle. A slight depression,
with just perceptibly angular sides, runs parallel to the occludent
margin. The scutal margin is nearly straight; with the exception of
this latter single character, scarcely any difference can be perceived
between this valve and that of P. glaber.

I have seen several large terga, (d,
natural size,) nearly an inch in length, from the Gault, which at first
appeared so different, that I thought them specifically distinct;
they

form the variation above alluded to. But, after careful comparison
of a large series, I feel convinced that the difference is caused
solely by age: the chief difference consists in the occludent margin
being considerably longer than the scutal margin, and consequently in
the widest part of the valve lying below the middle point: that
portion
of the valve, moreover, which lies on the carinal side of the
sub-central ridge is, in proportion, narrower than in the common form.
Internally, in these large specimens, a considerable portion of the
apex is marked by lines of growth: it follows from this, that if only
the internal corium-covered surfaces of the large and small terga be
compared, there is far less difference of outline than if they be
compared externally. I repeat that I have no doubt that these valves
all belonged to the same species.

Carina (Tab. 4, fig. 1a), closely like that of P.
glaber,
triangular, moderately tapering, very slightly bowed inwards; smooth,
sub-carinated, transversely slightly convex; lateral margins very
narrowly inflected, with the lines of growth curved downwards, and
those on the edge itself upturned; there is in this specimen a narrow,
slight, linear channel along the line where the lines of growth are
upturned; a small portion of the apex must have projected freely;
basal
margin (and consequently lines of growth) rounded, less angularly
protuberant than in P. glaber, with the two baso-lateral
angles slightly prominent.

Rostrum (fig. 1e),
triangular, rather more than half as wide and about half as long as the
carina, therefore rather wider in proportion to its length; more bowed
inwards; a very small portion of the apex, which is internally simply
concave, projected freely; basal margin curved, slightly protuberant:
exterior surface smooth, sub-carinated, like the carina; edges very
thin. Sub-rostrum (f) about half as long, and two
thirds as wide as the rostrum; apex rounded; basal margin not
protuberant; internally, slightly concave, with thin lateral margins,
widely overlapping the latera of the lower whorl; exterior surface not
subcarinated, that is, destitute of a central ridge.

Upper Latera (g),
elongated, triangular, flat, exteriorly smooth, except from the lines
of growth; two upper sides almost exactly equal in length, and
equalling once and a half of the length of the basal margin; entire
valve rather exceeding half the length of the terga.

Lower Latera: these consist of two small valves (l,
k),
namely (judging from the position in which, overlapping each other,
they were embedded), the first and second, or more probably the second
and third right-hand rostral latera of the lower whorl; and a pair (h,
i)
(right-hand and left-hand) of latera, of about twice the size of the
two anterior ones, which must have come from the carinal half of the
whorl, but the exact position of which I cannot tell. These latter
larger latera are thin, and considerably convex; they are transversely
elongated, and, in their longer axis, are rather more than half the
length of the terga of the same individual. In shape they may be almost
compared to one valve of a Donax; being sub-trigonal, with the two
upper sides unequal in length, and with the third side arched and
protuberant at a point about one third of the entire length of the
valve from the narrower end: to this protuberant point, a well-defined
ridge runs from the apex

of the valve; internally (i),
the lines of growth round the upper margins show that the two upper
sides and the apex overlapped freely the valves on each side of them.
This valve, as stated in the preliminary remarks, has naturally been
always mistaken for a scutum; but the manner in which it has
overlapped
other valves (as shown by the internal view), on both its upper
margins, and the entire absence of all hollow for the adductor muscle
prove that this view is quite erroneous.

The
two rostral or anterior small latera resemble each other (the anterior
one being a little the smallest), and likewise the largest carinal
latera just described; the external ridge, however, here runs to a
much
more nearly central point of the basal margin; and the shorter and
more
pointed portion of the basal margin is just perceptibly hollowed out.
The more pointed end is directed towards the carina. In the first latus
this end abuts against (no doubt thus producing) the external ridge on
the second latus, which it overlaps. Internally, under the apex, there
is a central crest (l), exactly as in the latera of the lower
whorl in large specimens of the recent P. mitella,
caused likewise by the overlapping of the valves: in the
above-described large carinal latera, however, this internal crest is
absent, showing that the arrangement of these latter valves differed
from that of the two anterior ones.

With respect to the
number of valves in the whole capitulum, it is almost useless to
speculate: we have two scuta, two terga, two upper latera, two rostra,
and we may, perhaps, infer two carinæ, making ten valves, we know of
three pair of lower latera, making sixteen valves: I believe there
must
have existed some other latera, but probably only a few more; for
these
valves, especially the carinal pair, are much larger, in proportion to
the scuta and terga, than in any recent Pollicipes. Probably the lower
latera, together with the sub-rostrum, and perhaps a sub-carina, formed
only a single lower whorl.

Size: in the individual
here described, the carina and terga, were equal in length to each
other, and .65 of an inch long. In Mr. Bowerbank's collection there is
a lower latus of nearly double the size of the same valve in this
individual, which shows that this species attains large dimensions.

Affinities. As before remarked, this species is very
closely related to the cretaceous P. glaber,
of which it is evidently the representative in the Gault; the chief
difference consisting in the more elongated form and greater size of
the upper latera, which, in P. unguis, exceed half the
length of the tergum, whereas in P. glaber
they are only one third of its length. The carina, in the present
species, has its basal margin, perhaps, less pointed, and has a narrow
linear channel along its edges; but I am not at all sure that this
latter character does not vary. Lastly, the anterior lower latera in P.
unguis
are thinner, and rather more convex, with the basal margin more arched
and protuberant, with the external oblique ridge very much more
central.

Considering the characters of both
species taken together, namely, the two ridges proceeding from the umbo
of the scuta to the baso-lateral angle and basal margin,—the triangular
shape of the upper latera,—the considerable size of the rostrum, and
the ridges

Scuta,
extraordinarily thick, narrow; occludent margin exteriorly
strengthened
by a rounded, strong ridge; internally, at the rostral angle, a blunt
tooth depends beneath the straight basal margin: the ridge running
from
the apex to the basal margin is nearer to the rostral than to the
baso-lateral angle. Carina very smooth, transversely semi-cylindrical;
upper freely projecting portion internally, either solid and flat, or
with a central prominent crest.

My
materials consist of several scuta and carinæ, sent me by Professor
Steenstrup as belonging to the same species, which is likewise the
opinion of that able collector, M. Angelin, who has found this species
in various localities in Scania. A very fine carina, from near
Maestricht, has been sent to me by Krantz, of Bonn.

Valves,
remarkably thick, massive, and strong. Scuta (fig. 2, e,
f, g, nat.
size) elongated, being twice as long as broad; slightly convex; whole
upper part bent towards the terga; surface, in some specimens, with
traces of longitudinal striæ. Basal margin formed obscurely (partly
owing to the rubbed condition of all the specimens), by two lines
meeting each other at a very open angle. Occludent margin much arched,
forming with the basal margin, taken as a whole, an angle of about 60°
:
tergo-lateral margin nearly straight, forming a rectangle with the
adjoining portion of the basal margin. That part of the valve formed by
the upturned zones of growth is narrow, being, in the widest part,
barely half the width of the other part of the valve. The occludent
margin is strengthened by a rounded, strong, projecting ledge, running
along its entire length; the basal end of this ledge, and consequently
the lines of growth crossing it, are oblique, and slightly upturned. A
slight ridge, or angle, runs from the apex to the baso-lateral angle,
and a second, still slighter ridge, to a point in the basal margin
rather nearer to the rostral than to the baso-lateral angle. Close to
the rostral angle, the internal lamina of the shell is
produced
downwards into a strong, blunt tooth, which (when not too much worn)
can be seen from the external side, depending beneath the basal margin
:
this is the most singular character of the species. The internal
occludent edge is broad (and of nearly the same breadth throughout the
whole upper part of the valve), flat, and marked by lines of growth:
this striated internal edge is separated from the smooth, depending,
rostral tooth, by a very oblique line. The pit for the adductor muscle
is very deep: above this pit there does not appear to have been any
furrow on either margin, or any marked central prominence.

Carina
(fig. 2, a, b, c, d, nat.
size), broad, extremely solid, much bowed
inwards; the upper part, even more than half the valve in length, must
have freely projected; exterior surface transversely semi-cylindrical,
or rather steeper than a semi-cylinder, but not at all carinated:
basal
margin not at all protuberant; lateral angles, or heels, just
perceptibly projecting below the central part of the basal margin: in
the Maestricht specimen it appears that there was a very slight furrow
near each exterior lateral margin, making them just perceptibly
protuberant. The internal, smooth, corium-covered surface is concave,
forming almost an equilateral triangle (b): above this, the
inner
freely projecting portion is either filled up flat, or forms a central
prominent crest (d).

Affinities. We shall immediately see that
this species appears to be most closely allied to P. gracilis,
of Roemer: it is also allied to P. dorsatus, by the strength
of the valves, by the occludent margin of the

of
all the valves, as far as is apparent, being downwards, and from their
number, apparently exceeding 16, I have, without hesitation, ranked
this species, (and consequently P. glaber,) under the genus
Pollicipes.

scuta
being exteriorly strengthened by a prominent ridge, and by the two
angular ridges running down to the basal margin, and by the general
character of the under surface of the apex: it differs widely from P.
dorsatus,
in the rostral, tooth-like process, and in the baso-lateral angle not
being widely truncated. The carina of these two species also presents
some points of similarity. In P. validus the centre of the
upper freely projecting portion often, but not always, has a
longitudinal crest or ridge: in the recent P. mitella,
the degree of filling up of the upper part of the carina varies
considerably, and sometimes even a central crest is formed in it.

Scuta
thin, narrow, occludent margin exteriorly strengthened by a rounded
ridge; internally at the rostral angle a blunt tooth depends beneath
the basal margin; the ridge running from the apex to the basal margin
is central. Internally there is a transverse furrow above the hollow
for the adductor muscle.

Roemer
has most kindly sent me a beautifully preserved scutum, which he has
fully described in the above quoted work. It is unfortunately rather
young, being .6 of an inch in length. It resembles so closely the same
valve in P. validus, that had it not already received a name
I should not have affixed one; still I think it is perhaps a distinct
species. It will be quite superfluous to do more than describe the few
points of difference, of which the chief and most conspicuous one is
the much greater thinness of the whole valve. I should, however, state
that I have not seen any specimen of P. validus so small, the
smallest being more than one third longer. The second chief difference
is that the medial longitudinal ridge here runs to a central point of
the basal margin instead of to a point nearer to the rostral angle. I
think the basal margin is more conspicuously formed by two distinct
lines, meeting each other at the above point. Internally the third and
perhaps most important distinction is the presence of a moderately deep
and large depression or fold, marked by lines of growth, extending
inwards from the occludent margin, just above the pit for the adductor
muscle, and as far inwards at the middle of the pit: this fold
precisely resembles that which occurs in the same position in Scalpellum
magnum, vulgare, and in some Pollicipes, as P.
Angelini.
The rostral tooth appears to have been larger. Owing to the thinness of
the valve, the internal occludent edge does not here present a flat
striated ledge.

I must again repeat that I
doubt whether the differences here pointed out are specific: I have
seen nearly all such peculiarities variable in other species. I am,
however, in some degree strengthened in leaving the P. gracilis
distinct, by the supposition that it is the representative species in
the true Chalk of the P. validus of the uppermost stage.

Scuta
thick, approaching to an equilateral triangle; occludent margin
exteriorly strengthened by a rounded ridge; baso-lateral angle widely
truncated, equalling half the length of the true basal margin;
tergo-lateral segment formed by the upturned lines of growth, extremely
narrow. Terga with a straight, broad, steep-sided ridge
running from
the apex to the basal angle, which latter on the scutal side is
obliquely truncated.

Faxoe; Denmark. Mus.
Univers.,
Copenhagen.

Professor
Steenstrup has kindly sent for my examination a large series of scuta,
terga, and carinæ, all from the same formation of Faxoe, and no doubt
belonging to the same species.

All the
valves are rather strong and thick; they are smooth, with the
exception
of the fine lines of growth. Scuta (fig. 4f, nat.
size, in a reversed
position compared with the other figures,) triangular, with the
baso-lateral angle largely truncated; considerably convex; breadth,
nearly equalling three fourths of length; apex acuminated, slightly
curved towards the terga. Occludent margin nearly straight, forming an
angle considerably less than a right angle with the basal margin; this
latter is short and nearly straight; the tergo-lateral margin is just
perceptibly concave; a very narrow slip is formed along this margin by
upturned lines of growth; this margin, if produced, would meet the
basal margin produced, at a less angle than the occludent margin does.
The baso-lateral angle is so largely truncated that the side so formed
is half the length of the proper basal margin, which it meets at a very
large angle; it is doubtful whether it should be called part of the
basal, or of the tergo-lateral margin; it touches, I suspect,
exclusively the latera, but in comparison with the other valves of this
genus I do not think it corresponds with the ordinary tergo-lateral
margin. Externally there is a slightly depressed line running from the
apex parallel and near to the occludent margin, causing this edge of
the valve to appear convex and protuberant; two slight ridges also run
from the apex—one to the angle uniting the basal and the
above-described truncated margin, and the other line, which is rather
fainter, runs down the valve half way between the first line and the
occludent margin. Internally, there is a deep, upwardly pointed pit for
the adductor muscle; the internal occludent edge keeps the same width
up to the apex; the internal tergal margin has no furrow, but is
slightly indented, and must have, to a certain extent, overlapped the
thin edge of the terga, and thus partly locked the valves together.

Terga
(fig. 4, d, e), rhomboidal, much elongated, almost
flat; occludent and
upper carinal margins (meeting each other at less than a right angle)
much shorter than the lower carinal and scutal margins. From the apex
to the basal angle, down almost exactly the middle of the valve, a
flat-topped ridge, either absolutely straight or nearly so, runs, and
widens considerably in its downward course; its carinal side is steep,
its opposite side less so; the oblique end of this ridge forms the
basal angle, which is nearly, but not exactly parallel to the upper
carinal margin. There is no depression parallel to the occludent margin.

Carina
(fig. 4, a, b, c) much elongated, very
slightly bowed inwards;
transversely, arched flatly; barely sub-carinated; basal margin
almost
rectangularly protuberant. Apparently, a full upper half of the carina
projected freely; this part is filled up flat and solid (c);
a rather
wide inner margin of the carina extending

arched
and protuberant; an obscure rounded ridge runs from the apex to the
baso-lateral angle; apex with the internal surface filled up solid,
without any distinct furrow.

Upper Chalk, Norwich. Mus.
Fitch.

My materials consist of two scuta, of which one is young; and of
some terga and a carina which I provisionally here describe.

Scuta (fig. 5, c),
broad, moderately convex; rather thick and strong; surface strongly
ribbed from the apex to the basal margin; ribs rather broad: apex
much
acuminated; occludent margin nearly straight, at right angles to the
basal margin, as is also the lower part of the tergo-lateral margin;
the upper part of this latter margin is inflected. A broad, very
slightly prominent ridge runs from the apex to the baso-lateral angle,
which is broad and rounded, but not prominent. There is no second ridge
from the apex to the basal margin, but along the line where such occurs
in P. glaber, the valve is rather abruptly arched; and in
the
younger specimens, a distinct trace of a ridge can be seen. Internally,
the pit for the adductor muscle is conspicuous; the whole upper part
of
the valve is filled up and rendered solid; the internal occludent edge
does not widen above the adductor pit; on the tergal margin a wide
internal ledge is marked by lines of growth, is slightly concave,
irregular, but not furrowed; on its surface, however, in the larger
specimens, there is, some little way below the apex, a small ridge and
linear hollow, which probably affected, in some peculiar way, the shape
of the terga; but I doubt whether this structure is constant. In
general external aspect, this valve comes nearest to the Scalpellum
arcuatum;
but its tergo-lateral margin not being angularly bent, its baso-lateral
angle not being prominent, and the greater width of the ridges easily
serve to distinguish it.

Terga (fig. 5, b; in a reversed position compared to
the other figures). Mr. Sowerby has figured a tergum in the '
Mineral Conchology,' Plate 606, fig. 1, under the name of P.
sulcatus,
from the Upper Chalk, and I have had given me by Mr. Woodward a second
specimen from the Upper Chalk of Norwich. From reasons stated under my
description of Scalpellum maximum, var. sulcatum, I
do not think it can belong to that species; and from one trifling
character, namely, the kind of ridge running from the apex to the basal
angle, most likely it belonged to a Pollicipes; and as only one
species
in the Norwich beds is as yet known to be ribbed longitudinally, I
believe that I have rightly attributed this valve to P. striatus.

almost
to the base, is marked by lines of growth, showing that the valve
rather widely overlapped the terga. Amongst the specimens there is one
very narrow valve, curled a little laterally as well as inwards; I
believe it to have belonged to a young and injured or monstrous
individual.

Affinities. The P. dorsatus,
though most readily distinguished from the P. elegans
of the same Faxoe formation, by the absence of ridges on the valves
parallel to the lines of growth, and likewise by the absence of a
strong ridge, running from the apex to the baso-lateral angle of the
scuta, certainly has a considerable affinity to it, as is particularly
manifest in comparing the terga of the two species; in the scuta of P.
elegans
(fig. 9 c) the truncated end of the oblique wall-sided ridge
is
obviously analogous with the broad truncated baso-lateral angle in P.
dorsatus. This species is also related, as we have seen, to P.
validus, and P. gracilis; again, also, it is related
to
the tertiary P. carinatus, and through it remotely to the
recent P. mitella.

Valve
much elongated, sub-rhomboidal; whole surface rather plainly ribbed
longitudinally. A larger rounded ridge, with the surface of the valve
depressed on the carinal side of it, runs in a slightly curved line, at
about one third of the entire width of the valve from the carinal
margin, down to the sharp basal angle. Apex narrow, much produced:
occludent margin about equal in length to the scutal margin: upper and
lower carinal margins almost running into each other. Parallel to the
occludent margin, the valve is depressed, with a raised plait in the
middle of the depression. Except in the more elongated form, and in the
character of the ridge running from the apex to the basal angle, this
valve is barely distinguishable from the tergum of S. arcuatum
(with its varieties) found in the Chalk Marl and Gault.

Carina (fig. 4, a).
In Mr. Tennant's collection there is a carina from the Chalk of Kent,
different from any other seen by me, and which, from being plainly
ridged, or rather furrowed longitudinally, I provisionally describe
here. Valve thin, triangular, moderately tapering; very
slightly bowed inwards; transversely, very flatly arched; plainly
subcarinated; lateral edges narrowly and much inflected; basal margin
rectangularly pointed. A very small portion of the valve projected
freely. The internal concavity of the valve is angular, instead of, as
usual, being rounded. The whole exterior surface, except close on each
side of the central ridge, is longitudinally furrowed.

Valves
longitudinally and transversely ridged; scuta with the basal margin
short, straight, forming a rectangle with the occludent margin; a very
narrow wall-sided ridge runs from the apex to the prominent
baso-lateral angle, and divides the valve into two unequal portions, of
which the tergo-lateral portion is the broadest.

Chalk Detritus, Charing, Kent. Mus.
Harris.

General Remarks.
I know this species only from one minute broken scutum (.15 of an inch
in length), with its surface somewhat disintegrated; but it is
certainly distinct from the other species hitherto described. The Chalk
detritus at Charing is derived from the upper and lower Chalk and Chalk
Marl.

Scutum; the surface is marked by narrow,
square-edged, longitudinal ridges, placed rather distant from each
other; each zone of growth appears (for the surface is much
disintegrated) to have had a prominent plait or ridge which,
consequently, runs in lines transverse to the longitudinal ridges. The
upper part of the valve is only moderately

pointed: the basal margin is short and straight; it forms, with
the
occludent margin, a right angle, and with the lower part of the
tergo-lateral margin, an angle rather above a right angle. A quite
narrow ridge, having perpendicular sides, only about twice as wide as
the other ridges, runs in a slightly curved course from the apex to the
baso-lateral angle; at which angle the ridge, as it appears, must have
formed a projection. The tergo-lateral portion of the valve, formed by
the upturned zones of growth, is unusually broad, rather exceeding in
width the rest of the valve; so that the ridge, running from the apex
to the baso-lateral angle, divides the valve into two only slightly
unequal portions, of which the tergo-lateral portion is the broadest.
Internally, the upper part, above the pit for the adductor muscle, is
along the middle, slightly prominent; on the tergal side, barely
furrowed, and on the occludent side, slightly hollowed out. This
species is allied to the three following species, and is, in some
respects, intermediate between them and P. striatus.

Valves transversely ridged. Scuta
with the basal margin straight, forming above a right angle with the
occludent margin; a wall-sided, very narrow ridge runs from the apex
to
the baso-lateral angle. Terga with a curved, wall-sided ridge
running to the basal angle, which latter terminates in a little,
parallel-sided projection.

General remarks.
This species appears rather common. I have scuta, terga, and carinæ,
which I infer without hesitation belong to the same species, from the
similarity of their peculiar surfaces, and from their having been found
frequently at the same place and in the same formation.

Description.
All the valves have their surfaces conspicuously marked with sharp,
narrow, steep-sided prominent plaits parallel to the lines of growth;
each periodical zone of growth seems to have been completed by the
formation of one of these projecting plaits; the interspaces between
the plaits, both on the scuta and carina, are either smooth, or more or
less plainly fluted with fine longitudinal ridges; these apparently
are
in some instances

only rendered visible or prominent by disintegration; the
transverse
plaits are also rendered more prominent by disintegration.

Scutum (Tab. IV, fig. 7, d, f)
elongated, triangular, but with the baso-lateral corner produced;
convex, with the upper part almost semi-conical; apex much pointed,
and
curved towards the carina; occludent margin considerably arched;
basal
margin short, forming, with the occludent margin, an angle considerably
above a rectangle, and therefore causing the baso-lateral angle to be
much produced. The tergo-lateral margin is in the upper part slightly
concave, in the lower part rounded and protuberant. The baso-lateral
angle is broad and rounded, but with a small, central, square-sided
prominence, formed by the projection of the ridge running from this
angle to the apex. This ridge is very conspicuous, it is narrow, being
not above one third of the width of an average zone of growth,
increasing very little in width downwards; it is wall-sided, that is,
has its sides absolutely perpendicular; its summit is surmounted by
transverse plaits, really continuous (but not at first appearing so)
with those on the surface of the valve on both sides of it. This ridge
runs in a curved line, nearly parallel to the occludent margin.
Internally (f), the occludent edge is broad and flat, and is
marked with lines of growth; it becomes wide at the apex; there is a
rather deep furrow close to the tergal margin, but there is no trace of
a central ridge; the pit for the adductor muscle lies quite close
under
the furrow and flat occludent edge; the nearest approach to this
structure of the under side of the apex of the scuta, is in the P.
glaber.

Terga (fig. 7, e).
On this valve the plaits, in specimens which have not undergone any
disintegration, are much less strongly pronounced than on the scuta and
carina; in shape, sub-rhomboidal, not quite flat; a curved,
wall-sided,
narrow ridge (like that on the scutum) runs from the pointed, slightly
curved apex to the sharp basal angle, and itself projects as a little
point, with parallel sides; the growth-plaits extend across this
ridge,
which runs at about one third of the entire width of the valve from the
carinal margin. The upper carinal margin is very slightly longer than
the lower carinal margin, with which it is almost blended by a
continuous curve. The occludent is shorter than the scutal margin; the
edge of the shell close to the former is rounded and protuberant, and
parallel to this rounded edge the valve is slightly depressed, and
correspondingly slightly hollowed out on the scutal margin; internally
there are lines of growth along the upper carinal and occludent
margins. Carina (fig. 7, a, b, c)
widening rather
slowly from the apex to the base; almost semi-cylindrical; very
slightly bowed inwards; not in the least carinated; basal margin not
at
all protuberant. The transverse plaits are, in the three specimens
which I have seen of the carina, undulatory; on the very narrow
lateral
margins (b) the plaits are obliquely upturned. The upper part
of the carina projected freely; this part, and both margins, are
internally marked by lines of growth.

Dimensions. Most of the specimens are rather small, but I
have seen one tergum seven-tenths of an inch in length.

Affinities. This species, with the two following P.
fallax and elegans, form a little group

closely related to each other, and in a far less degree to P.
dorsatus.
Some remarks on their diagnostic characters will be given under the two
following species. All three species are remarkable by the peculiar
form of their scuta, which have so much resemblance (especially in P.
rigidus)
to the terga of other cirripedes, that until I examined their under
surfaces I was not sure which valves they were. The conspicuous ridges
running obliquely downwards from the apices of the scuta and terga, I
have little doubt were due to the carina and rostrum largely
overlapping these valves, and to the presence of large upper latera, so
that the lower angles of the scuta and terga were closely wedged
between these valves.

Valves transversely ridged. Scuta,
with the basal margin not straight, forming nearly a right angle with
the occludent margin; a ridge having sloping sides runs from the apex
to the baso-lateral angle. Terga, with a curved ridge having
sloping sides, runs to the broad, rounded basal angle.

The
specimens which I have seen, consist of three right-hand scuta and one
tergum, in the possession of Mr. Fitch, from Norwich; of two scuta and
two terga collected by M. Angelin, in Scania, and forwarded to me by
Professor Steenstrup, and of a scutum from Hanover, sent to me by
Roemer, together with specimens of his P. uncinatus.

Description.
The valves are moderately thick; they are conspicuously marked with
rather wide prominent ridges, forming the basal edges of each zone of
growth; they seem in both scuta and terga most strongly developed near
the occludent margins.

Scuta (fig. 8, a)
almost triangular, moderately convex; occludent margin considerably
arched in the upper part, and bowed towards the terga; basal margin
not
straight, with a short portion close to the rostral angle forming a
rectangle with the occludent margin; the remaining portion, if
produced, would form a rather larger angle with it; hence the
baso-lateral portion of the whole valve is somewhat protuberant. The
tergo-lateral margin is in the upper part slightly hollowed out, and in
the lower part almost straight. A very slightly curved ridge runs from
the apex to the baso-lateral angle, which is broad, rounded, and not
prominent; the ridge has sloping, not wall-like sides. Internally the
structure of the upper part closely resembles that of P. rigidus.
The furrow on the tergal side is rather

narrower,
and a central portion of the inner occludent margin (marked with lines
of growth) here forms a slightly prominent ridge. In one of the three
specimens, the baso-lateral portion of the valve was considerably more
produced than in the other two. Terga (fig. 8, b),
rather broad, considerably convex; apex pointed, and much curled
towards the scuta; upper carinal margin unusually arched, slightly
longer than the lower carinal margin; there is a deep depression
parallel to the occludent margin, which is itself rounded, protuberant,
and considerably shorter than the scutal margin. A curved ridge,
projecting up above the general surface of the valve, with sloping
sides, runs from the apex to the basal angle, which latter is broad and
rounded; the ridge runs down nearly the middle of the valve.

Valves
longitudinally and transversely striated. Scuta with the
basal margin
straight, forming an angle rather above a rectangle with the occludent
margin; a wall-sided ridge, which is broader than the average width
of
the zones of growth, runs from the apex to the baso-lateral angle. Terga
with a straight, wall-sided ridge running to the pointed basal
angle.

Maestricht Formation, Faxoe, Denmark.
Ignaberga, Scania.

I
am indebted to Professor Steenstrup for an examination of three scuta,
a tergum and two carinæ, firmly embedded in the fragmentary coral-rock
of Faxoe, and of two very fine scuta from Scania, collected by M.
Angelin. The valves have each zone of growth raised into a ridge like
the roof of a house; the interspaces between these ridges are marked
by
longitudinal striæ. Length of largest scutum 1.1 of an inch.

Scuta
(fig. 9, c), with the apex acuminated, much curved towards
the terga;
occludent margin either slightly or much arched; forming an angle
rather above a right angle with the straight basal margin;
tergo-lateral margin slightly (but to a variable degree) hollowed out
in upper part, and nearly straight in the lower part, where it forms
nearly a right angle with the basal margin. Baso-lateral angle
generally very broad, rounded, almost obliquely truncated. From the
apex to this angle a gently curved, broad, wall-sided ridge runs, which
very perceptibly widens in its downward course; it is generally wider
than the average width of each zone of growth. Internally the occludent
margin is very wide, flat, and marked with ridges; the pit for the
adductor muscle is deep.

Terga (fig. 9, d)
broad, rhomboidal, slightly convex; basal angle apparently (for
specimen is broken) blunt, and obliquely truncated; upper carinal and
occludent margins nearly straight; shorter than lower carinal and
scutal margins; valve considerably depressed in a line parallel with
the occludent margin, close to which the margin itself is convex and
arched. The wall-sided ridge which runs from the apex to the basal
angle is straight, (not quite correctly represented at d),
and widens
considerably in its downward course: it is not so wide proportionally
to the whole valve as the ridge on the scuta, for it is here only a
little above half as wide as the average width of each zone of growth;
it runs at about one third of the width of the entire valve from the
carinal margin: the plaits cross its summit in a course not exactly
corresponding with those on the valve on each side of it; probably
this
ridge projected and formed, as in P. rigidus, the basal point
of the valve.

Carina
smooth, subcarinated; basal margin arched and protuberant; whole
valve
either outwardly bowed or nearly straight. Internally, the upper,
freely-projecting portion, has on each side a prominent ridge.

My
materials consist of some specimens lent me by the kindness of
Professor Steenstrup; they consist, as well as those described by
Roemer, only of the carina; their surfaces are considerably worn. The
Hils-conglomerat of Essen is considered by Roemer as the equivalent of
one of the lower beds of the Lower Greensand; but recently MM. Saemaan
and Geinitz have shown that it really corresponds with the Upper
Greensand. Professor Tennant has lent me a single broken carina from
Warminster, which cannot, in our present state of knowledge, be
specifically separated from the typical continental specimens, though,
as we shall see, slightly differing from them.

I will first describe the foreign specimens.

Carina (Tab. IV, fig. 10) strong, massive, triangular,
about twice as high as broad; but

what
bowed inwards; basal margin not in the least protuberant; not
carinated, but steeply convex, so that a section of the base (b)
has
steeper sides than a semi-circle.

Diagnostic characters. In comparing the
scuta of P.
rigidus, fallax, and elegans, the latter can
be at once distinguished from P. fallax by the ridge running
from the apex having perpendicular or wall-sides, and by the
straightness of the basal margin; from P. rigidus, by the
ridge being much broader; P. fallax differs from both, in
the
absence of longitudinal striæ. In the terga, P. elegans
differs from both P. rigidus
and fallax, in the ridge running from the apex to the basal
angle being
straight, and in its greater breadth, and likewise in the shortness of
the upper carinal margin. The terga of P. fallax differ from
the homologues of the other two species, in the ridge connecting the
upper and lower points, not having perpendicular sides.

the breadth varies with respect to the height; sub-carinated,
slightly bowed outwards or backwards, and therefore, in the opposite
direction to what is usual; but the amount of curvature varies much:
roof arched, inflected along the lateral edges; basal margin
protuberant, formed of two curved lines meeting each other at an angle
of above 90°. The lines of growth on the inflected lateral edges, curve
slightly downwards (b), and then just perceptibly upwards;
thus, no doubt, making the heels or two basal corners slightly
prominent. Internally, within the lateral edges (having the lines of
growth as just described), and separated from them by a distinct
indentation, there is on each side (b) a narrow ridge, widest
at about the middle of the upper half of the valve, and marked with
longitudinal lines of growth; these internal lateral ridges have
evidently been (as seen in the section) (d) formed during the
filling up and thickening of the upper, solid, outwardly bowed part of
the carina, which part, no doubt, projected freely. The lower part of
the carina (c) is deeply concave. Roemer describes the
exterior surface of the shell as marked with alternate finer and
stronger concentric lines, and rarely along the edges alone with
longitudinal lines.

The specimens from the
Upper Greensand of Warminster differ from the foreign specimens, in
being very slightly bowed inwards instead of outwards, and in having a
more tapering form; but it is precisely in these two respects, that
the
four foreign specimens seen by me vary to a considerable extent;
therefore, at present, the English specimens must be ranked under P.
Bronnii.

These
valves certainly differ considerably from any other known ones: the
slight outward bowing of the carinæ from the Hils-conglomerat is
their most conspicuous character, and was present in the four specimens
seen by me, and I presume, from Roemer's description, is general. In
recent species, however, the degree of curvature of the carina is often
variable: in P. spinosus, I have seen some specimens with
the
upper part of the carina even outwardly bent, and others with it
straight. The manner in which the upper part of the valve has been
filled up, having two lateral, inwardly projecting ridges, is unlike
any other species, and is the main specific character: the carinæ of Scalpellum
solidulum and of the var. cylindraceum of S. maximum
make the nearest approach to this structure. From such scanty materials
I will not pretend to say to what species this is most closely allied.

Terga subrhomboidal, broad, smooth, with the basal angle
widely truncated, and equalling in breadth half the length of the
occludent margin; the basal truncated side forms a right angle with
the
scutal margin: the uppermost part of the scutal margin forms a broad,
rounded, slightly projecting point.

Oxford Clay; Christian Malford and
Chippenham, Wilts. Mus. J. Morris.

This
species has been named by Mr. Morris, as it appears to me, from the
terga alone, which are well figured by him and by Mr. Sowerby: these
valves (an inspection of two of which from Chippenham, I owe to the
kindness of Mr. Morris,) are certainly quite distinct, in the extent to
which the basal angle is truncated, and in the degree of projection of
the uppermost part of the scutal margin, from any others which I have
seen; but had they not been already named, according to the rule
followed here, they would have been passed over.

Terga
subrhomboidal, or strictly pentagonal, rather broad, very flat and
thin; basal angle truncated, extraordinarily broad, equalling half the
length of the occludent margin, at right angles to the scutal margin;
no single distinct ridge, or furrow, runs from the apex to the broad
basal angle: upper and lower carinal margins nearly equal in length:
occludent and upper carinal margins meet each other at right angles:
occludent margin rather shorter than the scutal margin; with the
uppermost portion of the latter slightly projecting in a blunt, rounded
point, which corresponds with a just perceptibly convex slip of valve,
extending along the occludent margin in the manner so common in this
genus. Internally, the surface is smooth; scarcely even the smallest
part of the apex could have projected freely.

Largest specimen nearly a quarter of an inch in length.

[Published
species of Lepadidæ of a doubtful nature, owing to valves, not typical,
having been named, or from the specimens having been imperfect, or from
the shortness of the descriptions.]

Anatifera turgida.
Professor Steenstrup (in Kroyer's Tidsskrift, 2 B. (1839), Pl. V, figs.
4-5,) has thus named some valves from Scania: he states that the scuta
resemble in their growth those of Cineras, or his Anatifera cretæ,
that is the Scalpellum? cretæ of this work. Therefore, I
conclude that these valves cannot properly be ranked under Anatifera or
Lepas.

Anatifera convexa.
Roemer, Norddeutsch. Kreidegebirges, Tab. XVI, fig. 7. I do not
consider the evidence nearly sufficient to place the valve here
described in the genus Anatifera; it might be one of the lower Latera
of a species allied to Pollicipes glaber or unguis.
Pictet (Traité Elementaire de Paléontologie, Tom. III, p. 438) states
that the specimen in question is Aptychus cretaceus.
Several vague notices of fossil species of Anatifera or Lepas have
appeared at various times, but they hardly seem to deserve notice.

Pollicipes angustatus Geinitz (Die Verstein.
von
Kieslingswalde des Sächsisch-bohmischen, Kreidegebirges, 1843, Tab. IV,
fig. 10) is almost certainly a Scalpellum, and probably a new species;
the carina is narrow, bowed inwards, with the basal margin sharply
pointed; tectum carinated, separated from the parietes by a line or
ridge, which is said to be enclosed between two fine furrows; this
latter seems to be its most singular character. I cannot make out
whether it has intra-parietes; only a single view is given: found at
Strehlen, Saxony, in Pläner-Kalke (chalk-marl), and, according to the
same author, in his 'Das Quadersandsteingebirge" (p. 100); likewise
in Greensand, at Essen, in Westphalia.

The Pollicipes lævis of J. Sowerby, figured
in 'Geological
Transactions,' 2d series (1836), Vol. IV. Pl. XI, fig. 5, I consider
the same as his P. unguis, fig. 5*; but the P. lævis,
from Blackdown, Pl. XVI, fig. 1, seems to be certainly a distinct
species, and possibly a Scalpellum: no details are given. The P.
radiatus of the same author, of the lower greensand (Pl. XI, fig.
6), is unknown to me; the tergum figured is like that of S.
arcuatum; the upper valve, if a scutum, is very remarkable.

The name Pollicipes radiatus
has been a favorite with authors; there is a tertiary species so
called, but not described in 'Müller's Jahrbuch,' 1835. Koch and
Dunker, also, (Norddeutsch. Oolithgebildes, 1837,) have given this name
to a tergum found, according to Roemer, in the Hilsthon or Lower
Greensand; I conceive it to be scarcely possible, and very
inconvenient, to attach names to terga.

Michelotti has
called, without any description ('Bulletin, Géolog. Societé,' tom. 10,
p. 140), a tertiary Pollicipes from near Turin, P. antiquus,—a
most infelicitous name for a miocene species.

Roemer in his 'Die Versteinerungen des Norddeutsch.
Kreidegebirges,'
1841, has figured, Pl. 16, fig. 13, the above-mentioned P. radiatus,
of Koch and Dunker; also, Pollicipes asper
(Pl. 16, fig. 15), which is founded on a fragment of a carina, which I
have been permitted to inspect by the great kindness of Roemer; it is
not sufficiently perfect in the upper part to show whether it probably
belonged to Scalpellum or Pollicipes, but apparently to the latter
genus; it is almost certainly distinct from anything which I have seen; the tectum is very flatly arched, and the basal margin (as inferred
from the lines of growth) scarcely at all protuberant; it was very
slightly bowed inwards; its surface is covered with faint longitudinal
ridges, and these are crossed by concentric, leaf-like, projecting
lines of growth. The longitudinal ridges cause this valve to resemble
that of Scalpellum solidulum from Scania, but the basal
margin is much less protuberant, the tectum more steeply arched, and
the whole valve thicker than in that species. The P. asper
comes from the " Oberer Kreidemergel" (Upper Chalk) of Quedlinburg, in
Westphalia.

Roemer has also described in the same work (Pl. XVI,
fig. 10, a,
b, c,) Pollicipes uncinatus from the Upper
Chalk: the carina (b)
has its roof sharply carinated; its parietes are quite flat, and I
presume rectangularly inflected, which makes me suppose it may have
belonged to a Scalpellum; basal margin rectangularly pointed. The
valve, described as a tergum (c) I have had, through the
kindness of Roemer, an opportunity of examining; it cannot, I
conceive,
be a tergum; it is unknown to me; it appears to be a carinal latus;
if
so, the valve ought to have been placed in the figure transversely to
its present position.

Reuss in Die Verstein. der Bohmischen Kreideformation
(1845) has
figured (Tab. V, fig. 43) a carina, under the name of Pollicipes
conicus, from the Chalk; I do not consider it to be recognisable.
The P. glaber in this same work (Tab. V, fig. 45-49, and Tab.
XIII, fig. 86-91) appears to consist of several species; on the other
hand, P. radiatus (Tab. V, fig. 42) appears to be a scutum of
the true P. glaber.

and H. Von Meyer, 1848, 1 Band, p. 180, Tab. XXV,
fig. 14) has
described and figured a valve of Pollicipes liasinus:
he considers it as one of the great hinder lateral valves—that is, a
tergum. This eminent palæontologist is well acquainted with the
cirripedia, and is therefore probably right in his determination; but
I
am forced to say that the manner of growth seems to me, if I rightly
understand the figure, unlike that of the terga in any known
Pollicipes.

Müller (Aachen, p. 43, Tab. II, fig. 16,) has
described Pollicipes
ornatissimus; the valve figured is a carina, I believe, of Scalpellum
maximum.

The
specimens here figured by Mr. Sowerby, were found by Mr. Wetherell in a
deep well in the London Clay, at Hampstead, together with portions of Scalpellum
quadratum.
The specimens are in a broken condition, and have been kindly lent me
by Mr. Wetherell: they consist of some fragments of terga, and I
believe of the basal portion of a scutum, of a carina, and of several
latera. The species appears to have come near to the Eocene P.
reflexus;
but although thinking it distinct, I dare not, considering the
imperfect state of the scutum, name it. The valves appear to have been
much thicker and more rugged than those of P. reflexus; the
basal angle of the terga sharper, and the rostral angle of the scutum
more abruptly truncated. The latera are remarkable, and unlike anything
which I have seen; they present several shapes; they are all more or
less triangular, and their lateral edges are more or less distinctly
bordered exteriorly by prominent ridges; one has a central exterior
ridge, and its basal margin is protuberant; another has one of its
sides at right angles to the basal margin, and the other side largely
convex. Not having seen the lower latera of the P. reflexus,
or indeed of any fossil Pollicipes except of P. glaber and unguis,
I cannot use characters drawn from the latera as diagnostic. The
specimens are extremely small.

Capitulum with (perhaps) ten
valves. Peduncle with ten rows of smooth calcareous scales, of which
the six lateral rows are much elongated transversely, and the four end
rows narrow; along the rostral and carinal margins of the peduncle
there is a straight medial suture, with the scales not intersecting
each other.

Lower Chalk, Cuxton, near Rochester,
Kent. Mus. Wetherell.

I
owe to the kindness of Mr. Wetherell an examination of this beautiful
and unique specimen, well described and figured by Mr. G. B. Sowerby,
Junr., in the 'Annals of

Natural History.'1
I believe the specimen to be extremely incomplete; certainly only one
side of the capitulum and peduncle is preserved; but on this subject I
shall offer a few remarks after describing the specimen in its present
state. The specimen was embedded outside the cast of an Ammonite: Mr.
J. Morris informs me, that he has no doubt that the pit at Cuxton is
worked in the Lower Chalk.

The Capitulum (Plate
V, fig. 1, of nat. size,) consists of three left-hand valves, which are
small compared to the size and width of the peduncle, making me believe
that the greater part of the animal's body was lodged in the peduncle,
as in the recent genera, Lithotrya and Ibla. Of the three valves, I
believe from the general shape and direction of the lines of growth,
that one (on the right-hand side of the figure) is the scutum; of the
other two, I will at present call that nearest to the scutum the first
latus, and the other the second latus. The three valves are of nearly
equal size: they are very slightly convex, quite smooth, moderately
thick, with the lines of growth fine and obscure.

Scutum
(fig. 3) triangular, apex somewhat produced, and bowed over towards the
latera: occludent margin slightly arched, forming an angle much less
than a rectangle with the basal margin, which latter is at right angles
with the margin, called in Pollicipes tergo-lateral. The lines of
growth, in the lower part of the valve, are parallel to the
tergo-lateral and basal margins; and as far as I could distinguish in
the imperfect condition of of the valve, the valve is added to a little
during the growth of the apex, so that the umbo is not situated at the
uppermost point. In this important respect Loricula apparently
resembles the Scalpellum magnum, tuberculatum and cretæ.

The first (so called) latus
is nearly flat, triangular, with its apex on a level with that of the
scutum; the scutal margin (lying close and rather over the edge of the
scutum) is just perceptibly arched, and a very little longer than the
other lateral margin: the basal margin is shorter than the two lateral
margins; growth downwards.

The second (so called) latus
(fig. 2) is triangular, of nearly the same shape with the last valve,
with the inner basal angle a little produced; the outer margin is very
slightly arched, and is shorter than the inner margin; the main growth
is downwards, but the lines curl a little up and round the inner
margin. The apex of the valve in its present position stands a little
above the apices of the other two valves, and a wedge-formed open space
separates the upper part of the two latera.

Peduncle:
this has a most singular, elegant, loricated structure: it is wider
than the capitulum in the present condition of the latter, and about
four times as long. It is completely protected by large, smooth,
calcareous scales, of which five rows are preserved; and I conceive
there can be no doubt from the shape of the end rows, that there
originally existed a corresponding series on the opposite side, making
altogether ten rows. The base is sharply pointed, down to which the
full complement of scales extends. In each row

1
Since Mr. Sowerby made his description, Mr. Wetherell has cleared away
more of the Chalk, thus exposing a row of small scales at the carinal
end of the peduncle, not seen by Mr. Sowerby.

there
are about twenty-one scales, their numbers obviously depending on the
age and size of the individual. There is one more scale under the
second latus (fig. 4, restored figure), than under the first latus, and
one more under the first latus than under the scutum; hence the summit
of the peduncle is obliquely truncated, being lowest at the rostral
end: in this respect there is some resemblance to the genus Lithotrya.
The scales in the three lateral rows resemble each other pretty closely
in outline: they are transversely elongated, and are together about as
wide as the three valves of the capitulum; they are much longer than
the scales of either end row. The first row of these elongated scales
lies directly under the scutum, and the other two under the two latera; so that the lines of junction of the three rows of peduncular scales,
and of the three valves of the capitulum, correspond. The scales in the
middle row are rather longer than those on either side of it, are
pointed at both ends, and have their upper margin very flatly arched
and almost square-edged. The scales in the row under the second latus
are rather wider than it, projecting (which is important) beyond its
outer edge; their upper margins are square-edged; their outer ends
blunt and truncated; their inner ends pointed. The scales of the third
row under the scutum are rather less wide than it, and do not reach so
far as its outer or rostral angle; their upper margins are arched;
their outer ends bluntly rounded, and their inner ends pointed.

The
two end (that is, the rostral and carinal) rows of narrow scales remain
to be described: those at the rostral end (fig. 3) are as high as the
larger lateral scales, but only about one fourth as wide: in shape
they
are almost a rectangular oblong, with their upper ends a little
rounded, and the outer (with respect to the longitudinal axis of the
animal) basal angle a little produced; hence the two lateral margins
of
the scales of this rostral row do not quite match each other;
consequently, to make the animal symmetrical, there must have been a
corresponding approximate row of small scales on the other side of the
medial line. The straight inner (both sides of the peduncle being
supposed to be present) edges of the scales of the row just described,
extend rather beyond the occludent margin of the scuta. The scales in
the carinal row, at the opposite end of the peduncle, are not above
half the width of those of the rostral row: they are of nearly the
same shape,
but their upper ends are more pointed, and their outer (with respect to
the medial longitudinal axis of the animal) basal angles more produced; their straight inner margins projected considerably beyond the carinal
edge of the second latera: it is more obvious in this case than in the
rostral row, that there must have been a second adjoining row of small
scales on the other side of the carinal medial line. The small scales
of the carinal and rostral rows differ from the others in their inner
(that is, close to the medial axis), basal angles, not crossing each
other; so that the peduncle could have been divided in a medial
rostro-carinal plane, without cutting through a single scale. Their
outer basal angles, on the other hand, intersect the ends of the
adjoining large lateral scales, like these latter intersect each other,
the lines of intersection between them being straight and corresponding
with the junctions (as already stated) of the scuta and

latera. The consequence of this arrangement is, that in the
alternate whorls there are in one, four of the large lateral scales and
none of the smaller end scales; and in the whorl, both above and
below,
only two of these large lateral scales, and four of the carinal and
rostral scales; so that the alternate whorls (fig. 4) had an unequal
number of scales, namely, four and six.

Growth.—New
scales for the peduncle are formed round its upper edge, at the bases
of the valves of the capitulum, the chief growth of which, as we have
seen, is downwards: hence, we here have, as in other pedunculated
Cirripedia, a principal line of growth round the summit of the
peduncle. It can be seen that a new scale is first formed under the
second latus, at the carinal end of the peduncle; and this agrees with
the fact that there is one more scale in this row than in that next to
it; and one more in the latter, than in the row under the scutum. I
may
mention, as in conformity with this fact, that in the development of
the young of Scalpellum vulgare from the larval condition,
the calcareous scales on the peduncle first appear under the carina.

Attachment.—With
respect to the attachment, Mr. G. B. Sowerby seems to have felt great
difficulty on account of the peduncle ending in so fine a point; but
the peduncle of Scalpellum vulgare, when carefully dissected
from the coralline to which it is attached, often ends in a much finer
point, and is symmetrically attached to the branch by its narrow
rostral margin. In Loricula, the attachment was probably by one lateral
face of the lower part of the peduncle; for it is by no means unusual
for the cement-stuff (even when proceeding only from the two original
central orifices, where the prehensal antennæ of the larva may still be
found) to encroach largely on the peduncle, and thus fix it down. The
calcareous scales of Pollicipes, and the horny spines of Ibla, may
often be found thus embedded and firmly fixed to the supporting rock;
it is moreover possible, that in Loricula the cement was poured out of
orifices, specially situated on one side of the peduncle, as takes
place along the rostral margin in Scalpellum vulgare, and
high up on both sides of the peduncle in Lepas fascicularis.

Dimensions.—Entire length of the specimen rather above one
inch: width of widest part of the peduncle .6 of an inch.

On the probable condition of the Specimen when perfect.—I
have already remarked that the three valves of the capitulum, and the
five rows of scales on the peduncle, must have had an opposite series.
I at first thought it extremely improbable that the animal should have
been split so exactly down the middle; and I conceive, in most genera,
as in the common Lepas, it would be quite impossible to effect this;
but in removing the terga and scuta from one side of several specimens
in Ibla and Lithotrya, it was difficult to prevent exactly half of the
membrane of the peduncle (which in these genera is thin) being torn off
with them. Mr. G. B. Sowerby, jun., also has remarked (Annals of Nat.
Hist., 1843, p. 261), that, owing to the rostral and carinal rows of
small scales not intersecting each other, the splitting of the specimen
into halves along this plane would be much favoured. The inner edge of
the so-called second latus could not have touched the inner edge of its

fellow
valve on the opposite side, inasmuch as two small peduncular scales
were inserted between the ends of the larger peduncular scales, which
of themselves projected beyond the edges of the second latera: to fill
up this hiatus, I conceive there must have once existed a carina. For
the same reason, I believe, but less strongly, that there also existed
a rostrum. It may be observed that in the present condition of the
specimen, the straight lines of intersection between the two outer
large peduncular scales and the small rostral and carinal scales, do
not correspond with junctions of any valves in the capitulum; but if,
as in our imaginary figure (4), a carina and rostrum be added, the
above two lines of intersection will correspond with junctions of
valves in the capitulum; making altogether, on each side, in the
capitulum four lines of junction, and in the peduncle four lines of
intersection.

At present there is a wedge-formed open
space between the first and second latera; and judging from the lifted
up position (fig. 1) of the upper scales of the peduncle under the
second latus, this interspace must originally have been a little
larger. In order to complete the sack to receive and protect the
animal's body, this interspace must have been closed either by a valve
or by a membrane;—the latter supposition seems to me very improbable,
considering the closely loricated condition of the whole exterior;
consequently, I believe that on each side, a triangular valve with its
apex downwards was wedged in between the two latera, and that these
valves answered to the terga of other Cirripedes. On any other view,
considering the high improbability of the entire abortion of the terga,
we must conclude that either the first or second latus was a tergum,
though of a totally different shape from that valve in every other
pedunculated Cirripede; the other latus, moreover, would on such a
view
be a complete anomaly.

In the imaginary restored figure
(fig. 4), the tergum has its normal shape and manner of growth. The
first latus now answers to the upper latus in Scalpellum, but it is
interposed to a quite unprecedented extent between the scutum and
tergum. The second latus is on this view the carinal latus; and the
rostral latus, always smaller than the carinal latus, and in S.
quadratum and Peronii
reduced to a very small size, is here quite aborted. A restoration,
however, of this nature must always be very doubtful. Finally, I
imagine that the Loricula was attached by the side of the lower part of
its peduncle to some large shell or coral, and that a crab or some
other animal tore off the upper side, and this subsequently being
dropped, became embedded in the chalk; the corresponding valves with
the addition of a carina, rostrum, and a pair of terga being left
adhering to the surface of attachment.

Affinities.—In
an animal so imperfectly known, it is useless to enter on this subject
:
I will only remark that the restored figure comes nearest to the genus
Scalpellum; the recent S. ornatum has the scales on the
peduncle even proportionally more elongated than in Loricula. The chief
distinctive character of the genus, as at present imperfectly known,
lies in the arrangement of the scales on the peduncle. In those species
of Pollicipes, Scalpellum, and Lithotrya, in which the scales on the
peduncle are symmetrically arranged,

each
scale lies exactly between two scales in the whorls, both above and
below: this is, in fact, the case with the large lateral scales in
Loricula, but the ends of the scales in the same whorl, instead of, as
is usual, quite or nearly touching each other, are here far removed
from each other, so that each whorl is broken by wide open spaces. In
the marked difference in size between the lateral scales and those in
the two end rows;—in the latter scales not intersecting each other,
but
presenting a straight, medial, rostral and carinal suture;—and lastly,
in each alternate whorl having a different number of scales, namely,
four in one and six in the other, Loricula differs from every other
known Cirripede.

[N.B.—A left-hand scutum (fig. 4,
f), and a left-hand tergum (fig. 5, b),
have been accidentally figured
instead of right-hand valves, as in all the other Figures and Plates;
hence these two hold reversed positions, and in both the occludent
margins are to the right, instead of to the left hand.]

Fig. 1. Pollicipes unguis; all the figures except (d)
are from the same individual and are magnified twice: (d) is
of the natural size.

(a) Carina.

(b) Tergum, inside view.

(c) Ditto, outside view.

(d) Ditto, ditto, (var., natural
size.)

(e) Rostrum.

(f) Sub-rostrum.

(g) Upper latus.

(h) Latus of the lower whorl, probably
adjoining the carina.

(i) Ditto, inside view.

(k) Latera of the lower whorl, probably the
two adjoining the rostrum.